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Cycle
16 Abstract catalog (based on Phase I submissions)
Generated
on:
Mon
Apr 9 12:08:20 EDT 2007
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11099
Title:
A
"silver bullet" for the sources of reionization
PI:
Marusa
Bradac
PI
Institution:
Stanford
University
Recent
discoveries of z>6 galaxies have given us the first glimpse of the
Universe
shortly after the era of reionization. The questions arose whether
these
first galaxies can be made responsible for the reionization process, and
how
long did it last. Neither observations nor theory provide a clean
answer.
In
particular observations give results that are barely mutually consistent
and
need to be further tested. Observing high redshift (z>7) sources is
in
general
difficult, mostly due to the high luminosity distance to these
objects,
and partly due to the lower expected stellar masses compared to
objects
at moderate redshifts. We
propose to use one of the most massive,
merging
cluster 1E0657-56 (z=0.295) as a cosmic telescopes to efficiently
probe
the high-redshift universe. The gravitational potential well of this
cluster
provides several magnitudes of magnification, enabling study of
intrinsically
lower luminosity galaxies.As we discuss in the proposal, due to
its
highly elongated mass distribution and ideal redshift the bullet cluster
is
a prime candidate for this study. We propose deep NICMOS and WFPC2
observations;
with much reduced observing time compared to e.g. NICMOS UDF we
expect
an order of magnitude more (~5 candidates) z>7 objects. They will
also
likely
be multiply imaged, and since the geometry of images depends upon the
redshift,
we will be able to confirm their nature, thereby not requiring
(often
prohibitive at these magnitudes) spectroscopic follow-up. This will
enable
us to count high-redshift sources and constrain their luminosity
function;
a task made possible with the help of gravitational lensing even in
the
pre-JWST era.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11100
Title:
Two
new `bullets' for MOND: revealing the properties of dark matter in
massive
merging clusters
PI:
Marusa
Bradac
PI
Institution:
Stanford
University
The
principal objective of this proposal is to study the physical nature of
dark
matter by using two, massive, newly-identified merging clusters of
galaxies.
As shown by the pioneering example of the ``bullet cluster''
(1E0657-56),
such systems are ideal laboratories for detecting dark matter and
distinguishing
between cold dark matter (CDM) and other scenarios (e.g.
self-
interacting
dark matter). Our limit on the self-interaction cross-section of
dark
matter relies on the assumption of a normal pre-merger mass-to-light
ratios,
and a small impact parameter during the collision of the two clusters.
In
order to mitigate any possible systematic effects, it is vital to extend
this
work to other, similar systems. With detailed observations of new
systems,
the systematic uncertainties in the dark matter cross section
calculations
can be improved substantially, allowing us to move from rough
order
of magnitude estimates to measurements with quantifiable uncertainties
that
can be compared usefully with the predictions from numerical
simulations.
Our
targets are two extraordinary, high-redshift, merging galaxy clusters
recently
discovered by the Massive Cluster Survey (MACS). This
survey is by
far
the best matched to this study, since it selects medium redshift
(optimal
for
gravitational lensing studies) and X-ray luminous (hence massive)
objects.
We
have selected the best candidates with clear evidence for considerable
offsets
between the hot X-ray emitting gas and optically luminous stellar
material.
The two most striking examples are the targets of this proposal. To
pin
down the position of the dark matter component we require high
resolution,
absolutely
calibrated mass maps. The combination of weak and strong lensing
measurements
is needed to attain this goal. This can only be achieved with the
excellent
resolving power of the HST (in combination with wide-field,
multicolor
Subaru data already in hand). We
therefore request multicolor
HST/WFPC2
observations of the two merging clusters. The combination of
constraints
from multiply lensed images (identified via morphology and color
information)
and high-resolution weak lensing data will allow us to construct,
self-consistently,
their mass distribution from the very centers to the
outskirts.
Gravitational lensing thus provides a unique tool transforming
these
clusters into dark matter laboratories. They will supply us with answers
as
to the nature and properties of dark matter, and how it shapes galaxies
and
galaxy
clusters and their evolution through cosmic time.
======================================================================
Proposal
Category: GO
Scientific
Category: AGN/QUASARS
ID:
11101
Title:
The
Relevance of Mergers for Fueling AGNs: Answers from QSO Host Galaxies
PI:
Gabriela
Canalizo
PI
Institution:
University
of California - Riverside
The
majority of QSOs are known to reside in centers of galaxies that look
like
ellipticals.
Numerical simulations have shown that remnants of galaxy mergers
often
closely resemble elliptical galaxies. However, it is still strongly
debated
whether the majority of QSO host galaxies are indeed the result of
relatively
recent mergers or whether they are completely analogous to inactive
ellipticals
to which nothing interesting has happened recently.
To address
this
question, we recently obtained deep HST ACS images for five QSO host
galaxies
that were classified morphologically as ellipticals (GO-10421). This
pilot
study revealed striking signs of tidal interactions such as ripples,
tidal
tails, and warped disks that were not detected in previous studies. Our
observations
show that at least some "elliptical" QSO host galaxies are the
products
of relatively recent merger events rather than old galaxies formed at
high
redshift. However, the question remains whether the host galaxies of
classical
QSOs are truly distinct from inactive ellipticals and whether there
is
a connection between the merger events we detect and the current nuclear
activity.
We must therefore place our results into a larger statistical
context.
We are currently conducting an HST archival study of inactive
elliptical
galaxies (AR-10941) to form a control sample. We now propose to
obtain
deep HST/WFPC2 images of 13 QSOs whose host galaxies are classified as
normal
ellipticals. Comparing the results for both samples will help us
determine
whether classical QSOs reside in normal elliptical galaxies or not.
Our
recent pilot study of five QSOs indicates that we can expect exciting
results
and deep insights into the host galaxy morphology also for this larger
sample
of QSOs. A statistically meaningful sample will help us determine the
true
fraction of QSO hosts that suffered strong tidal interactions and thus,
whether
a merger is indeed a requirement to trigger nuclear activity in the
most
luminous AGNs.
======================================================================
Proposal
Category: GO
Scientific
Category: SOLAR SYSTEM
ID:
11102
Title:
HST
as a Jovian Climate Satellite
PI:
Imke
de Pater
PI
Institution:
University
of California - Berkeley
In
the past year, there have been striking changes in Jupiter's atmosphere.
Among
these are the Oval BA's change from white to red, two new dark
Disturbances
in the southern hemisphere, and a 30% change (since 1997) in the
aspect
ratio of the potential vorticity anomaly of the GRS (not just its
associated
clouds), as we determined from high-accuracy velocities extracted
from
HST images. The determination of high-accuracy velocities requires both
high-resolution
imaging by HST (or flybys), and our novel adaptation of
Correlation
Image Velocimetry (CIV), a technique that has far greater accuracy
than
the traditional method (of identifying velocity tie-points by hand). Our
proposed
observations will test the hypothesis that these changes in Jupiter
validate
our 2004 prediction:
that
the merger of the 3 White Ovals in 1998-
2000
would lead to climate change on Jupiter. The key is to determine, by
indirect
means, the temperature at the base of
the weather layer, a quantity
that
cannot be observed directly at any wavelength. The new Red Oval BA's
velocities
will be used to test our finding that the color change is due to
global
temperature changes. The change in the GRS's aspect ratio suggests a
large
(at least 20%) change in the shear of the local velocity since 1997. The
latter
can be investigated only by determining Jupiter's current zonal winds.
======================================================================
Proposal
Category: SNAP
Scientific
Category: COSMOLOGY
ID:
11103
Title:
A Snapshot Survey of The Most
Massive
Clusters of Galaxies
PI:
Harald
Ebeling
PI
Institution:
University
of Hawaii
We
propose the continuation of our highly successful SNAPshot survey of a
sample
of 125 very X-ray luminous clusters in the redshift range 0.3-0.7. As
demonstrated
by the 25 snapshots obtained so far in Cycle14 and Cycle15 these
systems
frequently exhibit strong gravitational lensing as well as spectacular
examples
of violent galaxy interactions. The proposed observations will
provide
important constraints on the cluster mass distributions, the physical
nature
of galaxy-galaxy and galaxy-gas interactions in cluster cores, and a
set
of optically bright, lensed galaxies for further 8-10m spectroscopy. All
of
our primary science goals require only the detection and
characterisation
of
high-surface-brightness features and are thus achievable even at the
reduced
sensitivity of WFPC2. Because of their high redshift and thus compact
angular
scale our target clusters are less adversely affected by the smaller
field
of view of WFPC2 than more nearby systems. Acknowledging the broad
community
interest in this sample we waive our data rights for these
observations. Due to a clerical error at STScI
our approved Cycle15 SNAP
program
was barred from execution for 3 months and only 6 observations have
been
performed to date - reinstating this SNAP at Cycle16 priority is of
paramount
importance to reach meaningful statistics.
======================================================================
Proposal
Category: GO
Scientific
Category: AGN/QUASARS
ID:
11104
Title:
The
nature of radio transients
PI:
Avishay
Gal-Yam
PI
Institution:
California
Institute of Technology
We
have conducted the first ever blind, wide-field survey for radio
transients
(Levinson
et al. 2002; Gal-Yam et al. 2006). We have discovered four radio
transients
and explored their nature using radio and optical follow-up
observations.
One is a known pulsar, one is a z~0.1 AGN, and one is most
probably
an optically obscured radio supernova (SN) in the nearby galaxy NGC
4216
(the first such event to be discovered by a wide field radio survey).
The
last
source appears not to be associated with a bright host galaxy (to a
limit
of
R < 24.5 mag). We request 4 orbits of WFPC2 F606W imaging to check
whether
we
can establish an association between this radio transient and any of
three
nearby
faint resolved galaxies we have detected from the ground. If the source
is
associated with any of these galaxies it would represent a new type of
extra-galactic
radio bursts, more luminous than, e.g., radio afterglows of
gamma-ray
bursts. Alternatively, ruling out an association with these galaxies
would
disfavor an extra-galactic nature of this object, and suggest instead
that
this is a radio outburst of a faint Galactic compact object, probably a
new
type of radio-flaring neutron star. If this is the case, the high
luminosity
(9 mJy) and relatively high galactic latitude (33 degrees) of this
source
may indicate it is relatively nearby. This single source represents a
large
population (comparable in sky density to AGN, pulsars, and radio SNe)
and
thus merits intensive study. A modest investment of HST time, leveraged
by
massive
ground-based radio and optical efforts, will allow us to identify a
new
class of radio sources, and complete a census of the variable radio sky
down
to ~6 mJy, leaving no unidentifed objects. This result can be directly
scaled
to predict the number and type of transient sources expected to be
detected
by future surveys with the next generation radio arrays, such as ATA
and
SKA.Since our science critically requires HST's spatial resolution
(rather
than
sensitivity) it is perfectly suited to be carried out with WFPC2.
======================================================================
Proposal
Category: GO
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11105
Title:
The
LBV progenitor of SN 2005gl - a new key to massive star evolution
puzzles
PI:
Avishay
Gal-Yam
PI
Institution:
California
Institute of Technology
The
currently accepted theory regarding the last stages of massive star
evolution
maintains that the evolution of the envelope is coupled to that of
the
stellar core. For this reason, very massive stars are expected to shed
their
outer hydrogen envelopes before they develop large iron cores, and
ultimately,
explode as core-collapse supernovae (SNe). It is therefore a
strict
prediction of current models that massive stars (certainly those above
~40
solar mass) will explode as hydrogen-poor SNe, i.e., of Types Ib and Ic.
In
particular, the class of luminous blue variables (LBVs) such as
eta-Carina,
which
are known to be very massive (up to 100 solar masses and above) are
expected
to lose their entire hydrogen envelopes prior to their ultimate
explosions
as SNe. However, using pre-explosion HST/WFPC2 imaging of the
location
of the recent hydrogen-rich type IIn SN 2005gl, we have identified
(Gal-Yam
et al. 2007) its putative progenitor as a very luminous point source
(with
absolute V magnitude of -10.2). If this is a single star, it must be an
LBV
from luminosity considerations (no other stars are as luminous). If our
progenitor
identification is correct, at least in some cases, massive stars
explode
before losing most of their hydrogen envelope, indicating the core and
envelope
are decoupled, and requiring revision of stellar evolution theory.
Here,
we propose a single-orbit HST observation of the location of SN 2005gl
designed
to test whether the point source we identified as its LBV progenitor
has
indeed disappeared (as expected from a single star) or remained
unchanged
(as
expected, e.g., if it is a compact star cluster). These data are the
last
observational
ingredient required to firmly establish (or refute) the
explosion
of an LBV as a type IIn SN, with fundamental implications for the
theory
of massive star evolution. Since the new data will be compared to pre-
explosion
WFPC2 images, this program is perfectly suited to be carried out
with
the WFPC2 camera.
======================================================================
Proposal
Category: GO
Scientific
Category: SOLAR SYSTEM
ID:
11106
Title:
Target
of Opportunity Imaging of an Unusual Cloud Feature on Uranus
PI:
Heidi
Hammel
PI
Institution:
Space
Science Institute
The
planet Uranus is demonstrating increased atmospheric activity as it
approaches
its 2007 equinox, perhaps in response to extreme insolation change.
Convective
sites in the planet's southern hemisphere reached unprecedented
altitudes
in 2003 (Hammel et al. 2005, Icarus 175, 284); a bright northern
feature
showed the highest contrast yet detected in an outer planet atmosphere
(Sromovsky
et al. 2007, Icarus, submitted); and a dark atmospheric feature was
detected
by HST for the first time (Hammel et al. 2007, in preparation). The
historical
record makes references to discrete structures (both bright and
dark)
on Uranus during previous equinoctial apparitions (the last equinox
occurred
in 1965). The best amateur
facilities are now just able to resolve
the
disk of Uranus and detect such activity if it is very large or has very
high
contrast. Amateurs also have
access to a great many nights of telescope
time. If a discrete cloud feature on Uranus
is reported through the amateur
network,
we propose to obtain follow-up images with HST's WFPC2.
The proposed
TOO
images will permit determination of detailed structure of the feature at
visible
wavelengths, and will provide vertical and horizontal constraints on
the
feature's scattering properties.
HST is the only facility that can
provide
such information at visible wavelengths.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11107
Title:
Imaging
of Local Lyman Break Galaxy Analogs: New Clues to Galaxy Formation in
the Early
Universe
PI:
Timothy
Heckman
PI
Institution:
The
Johns Hopkins University
We
have used the ultraviolet all-sky imaging survey currently being
conducted
by
the Galaxy Evolution Explorer (GALEX) to identify for the first time a
rare
population
of low-redshift starbursts with properties remarkably similar to
high-redshift
Lyman Break Galaxies (LBGs). These "compact UV luminous
galaxies"
(UVLGs) resemble LBGs in terms of size, SFR, surface brightness,
mass,
metallicity, kinematics, dust, and color. The UVLG sample offers the
unique
opportunity of investigating some very important properties of LBGs
that
have remained virtually inaccessible at high redshift:
their morphology
and
the mechanism that drives their star formation. Therefore, in Cycle 15
we
have
imaged 7 UVLGs using ACS in order to 1) characterize their morphology
and
look
for signs of interactions and mergers, and 2) probe their star formation
histories
over a variety of timescales. The images show a striking trend of
small-scale
mergers turning large amounts of gas into vigorous starbursts (a
process
referred to as dissipational or "wet" merging). Here, we propose to
complete
our sample of 31 LBG analogs using the ACS/SBC F150LP (FUV) and WFPC2
F606W
(R) filters in order to create a statistical sample to study the
mechanism
that triggers star formation in UVLGs and its implications for the
nature
of LBGs. Specifically, we will 1) study the trend between galaxy
merging
and SFR in UVLGs, 2) artificially redshift the FUV images to z=1-4 and
compare
morphologies with those in similarly sized samples of LBGs at the same
rest-frame
wavelenghts in e.g. GOODS, UDF, and COSMOS, 3) determine the
presence
and morphology of significant stellar mass in "pre-burst" stars, and
4)
study their immediate environment. Together with our Spitzer
(IRAC+MIPS),
GALEX,
SDSS and radio data, the HST observations will form a unique union of
data
that may for the first time shed light on how the earliest major
episodes
of
star formation in high redshift galaxies came about.
This proposal was
adapted
from an ACS HRC+WFC proposal to meet the new Cycle 16 observing
constraints,
and can be carried out using the ACS/SBC and WFPC2 without
compromising
our original science goals.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11108
Title:
Near
Infrared Observations of a Sample of z~6.5-6.7 Galaxies
PI:
Esther
Hu
PI
Institution:
University
of Hawaii
The
majority of the most distant galaxies discovered to date have been found
by
strong Lyman alpha emission at red optical wavelengths.
An accurate
estimate
of the star formation rates for
these objects requires a measurement
of
the line-free UV continuum, which must be taken at infrared wavelengths.
Here
we propose to obtain imaging with NICMOS in the F160W filter for a
sample
of
9 Lyman alpha galaxies with redshifts z~6.5 up to z=6.740 from a
complete,
flux-limited
widefield narrowband and multi-color survey conducted on the 8-m
Subaru
Telescope. This program will investigate galaxy morphologies and star
formation
for a uniform sample of the highest redshift galaxies now known.
======================================================================
Proposal
Category: GO
Scientific
Category: SOLAR SYSTEM
ID:
11109
Title:
Characterization
of the UV absorption feature in asteroid (1) Ceres
PI:
Jianyang
Li
PI
Institution:
University
of Maryland
We
propose to obtain the UV spectrum of asteroid (1) Ceres from 120 nm to
200
nm
with ACS/SBC objective prism to characterize the broad and deep
absorption
feature
within this wavelength range as reported recently.
Our scientific
goals
include, 1) to characterize the absorption band, 2) to determine the
origin
of this spectral feature and constrain the surface compositions of
Ceres,
and 3) to understand the albedo and color features on Ceres. HST is
the
only observatory currently capable of obtaining spectroscopy in this
wavelength
range. This observation will help
improve our knowledge about this
largest
and oldest asteroid, and support the planning of the upcoming NASA
Discovery
Program mission, Dawn, orbiting asteroids Vesta and Ceres.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM IN EXTERNAL GALAXIES
ID:
11110
Title:
Searching
for Lyman alpha Emission from FUSE Lyman Continuum Candidates
PI:
Stephan
McCandliss
PI
Institution:
The
Johns Hopkins University
We
have recently been granted time on FUSE to characterize the escape
fraction
of
hydrogen Lyman continuum (Lyc) photons from a morphologically diverse
set
of
star forming galaxies. The FUSE
program is designed to provide ~ 5 sigma
detections
of Lyc photons emitted from star
forming galaxies with escape
fractions
~5%. With this proposal we seek
hydrogen Lyman alpha (Lya)
observations
of a representative subset of the FUSE program targets to
constrain
the observational relationship between Lyc, Lya, and hydrogen Balmer
line
emission in these systems. Such
observations explore the detailed
balance
between the simple optically thin (Case A) and optically thick (Case
B)
limits in recombination theory.
The ultimate goal of this program is to
quantify
the relationship between escaping Lya and Lyc emission and the first
structures
that form in the early universe.
======================================================================
Proposal
Category: GO
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11111
Title:
A
Search for an Intermediate Mass Black Hole in the Globular Cluster NGC
6266
PI:
Bernard
McNamara
PI
Institution:
New
Mexico State University
We
propose to search for an intermediate mass black hole (IMBH) in the
core of
the
galactic globular cluster NGC 6266. Based on a comparison between the
observed
central surface brightness profiles of 38 globular clusters and
state-of-the
art N-body simultations, NGC 6266 offers the best hope of
detecting
an IMBH among these objects. This detection would be significnat for
at
least two reasons. It would be the first concrete discovery of an IMBH,
revealing
unique information about the environment in which these objects
form,
and second, its discovery would provide a powerful validation on the N-
body
simultations used to track the dynamical evolution of globular clusters.
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11112
Title:
The
Collisional Ring Galaxy NGC922
PI:
Gerhardt
Meurer
PI
Institution:
The
Johns Hopkins University
We
request WFPC2 images of the newly recognized collisional ring galaxy
NGC922
which
will become the nearest such system observed by HST. These will be used
to
get a clear understanding of the geometry of the interaction and the
induced
star formation in this system.
Quantitive modeling of the colors of
the
star clusters and stellar populations will be used to constrain the star
formation
history of the system. They will
also be used to test the "infant
mortality"
scenario for star cluster evolution. The derived population ages
will
test predictions of how star formation evolves in the various components
(ring,
core, spokes) of collisional rings, and will improve our own
simulations
of this system. These will be used
to determine the final fate of
the
stars formed in the present burst - some will end up in a central bar or
bulge
while others will become part of a thickened disk.
By analogy this will
tell
us how similar collisions enrich stellar populations in the early
universe. This is especially relevant since the
number density of collisional
rings
increases rapidly with redshift.
======================================================================
Proposal
Category: SNAP
Scientific
Category: SOLAR SYSTEM
ID:
11113
Title:
Binaries
in the Kuiper Belt:
Probes
of Solar System Formation and Evolution
PI:
Keith
Noll
PI
Institution:
Space
Telescope Science Institute
The
discovery of binaries in the Kuiper Belt and related small body
populations
is powering a revolutionary step forward in the study of this
remote
region. Three quarters of the
known binaries in the Kuiper Belt have
been
discovered with HST, most by our snapshot surveys.
The statistics
derived
from this work are beginning to yield surprising and unexpected
results. We have found a strong concentration of
binaries among low-
inclination
Classicals, a possible size cutoff to binaries among the Centaurs,
an
apparent preference for nearly equal mass binaries, and a strong
increase
in
the number of binaries at small separations. We
propose to continue this
successful
program in Cycle 16; we expect to discover at least 13 new binary
systems,
targeted to subgroups where these discoveries can have the greatest
impact.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11114
Title:
Improving
proper motion measurements of the
stars in the field of SN 1572 with WFPC2
PI:
Pilar
Ruiz-Lapuente
PI
Institution:
Universidad
de Barcelona
We
propose to complete the spatial velocity measurements of the stars in
the
central
region of the remnant of SN 1572, one of the historical Galactic Type
Ia
supernovae. A new visit with WFPC2 would allow us to significantly
improve
the
accuracy of the proper motion measurements of the stars in the field,
since
we would benefit from a long temporal baseline by using the WFPC2 images
previously
taken. This unique legacy would complement the high-precision
ground-based
observations made for the stars in the SN 1572 field during the
past
ten years. The search for the companion star of Galactic Type Ia
supernovae,
based on their high peculiar velocity as a salient feature, has
already
pointed to a good candidate for SN 1572. The current uncertainties in
the
tangential velocity of the candidate star and the other stars in the
field
can
be reduced to less than a half with a visit in Cycle 16. This would lead
to
a precise determination of the parameters of the binary system that gave
rise
to the supernova. If not done during Cycle 16, the long temporal
baseline
for
SN 1572 with WFPC2 would be lost.
======================================================================
Proposal
Category: GO
Scientific
Category: SOLAR SYSTEM
ID:
11115
Title:
Photometric
Imaging of Asteroid 2 Pallas
PI:
Christopher
Russell
PI
Institution:
University
of California - Los Angeles
We
propose to conduct the first HST imaging of Asteroid 2 Pallas with
WFPC2-PC
over
8 HST orbits. We will image the
asteroid in five filters: F336w,
F439w,
F555w,
F675w and F814w. We will utilize
these observations to drastically
improve
the knowledge of Pallas' shape, spin pole position and surface
properties,
including roughness and albedo, parameters that are poorly
determined
by previous study. These observations will result in high signal-
to-noise,
high resolution surface maps from the visible to the UV.
A
satellite
search will also be conducted for objects within the stability field
of
up to 21st magnitude, or about 900m in diameter. It
is demonstrated in our
proposal
that significant scientific opportunity exists in Cycle 16 because
Pallas
is at both a low-phase, 3.9 degree opposition and near its closest
approach
to Earth, conditions that do not occur simultaneously in the next
twenty
years. This window represents the
best chance to answer long standing,
fundamental
questions about Pallas, the main asteroid belt, and the formation
of
the solar system.
======================================================================
Proposal
Category: GO
Scientific
Category: COOL STARS
ID:
11116
Title:
Exploring
the Early FUV History of Cool Stars: Transition Regions at 30 Myr
PI:
Steven
Saar
PI
Institution:
Smithsonian
Institution Astrophysical Observatory
Stellar
magnetic activity derives from the so-called "dynamo," a
hydromagnetic
interplay
between overturning plasma motions and differential rotation in
stars
cool enough to support significant surface convection zones. The
magnetic
fields resulting from dynamo action are in turn are responsible for a
wide
range of high-energy emissions, including the spectacular outbursts
called
flares. Dynamo powered magnetic
activity is not confined solely to
stars,
but also must occur, for example, in accretion disks of all
descriptions,
and in some planets. A great deal
is known about magnetic
activity
in middle-aged G dwarfs like our Sun, thanks to its proximity. Less
is
known, however, about the much younger stars, newly emerged from the T-
Tauri
stage. Yet, it is during this
phase that they reach the peak of their
magnetic
activity, and subsidiary influences, such as the impact of ionizing
radiation
and strong coronal winds on developing solar systems, also are
maximum. One of the key missing ingredients in
our current understanding are
measurements
of FUV emissions of such stars, to complement the extensive
collections
of coronal (1-10 MK) X-ray measurements, particularly from recent
ROSAT,
Chandra and XMM-Newton surveys. We
propose to conduct sensitive
ACS/SBC
prism ultraviolet spectroscopy of selected fields in two young (30
Myr)
Galactic clusters--IC 2391 and IC 2602--to inventory the key C IV
emission
index (~0.1 MK) over a much larger and more diverse sample of coeval
objects
than has been possible hitherto. A
key question is whether the FUV
emissions
also suffer the "saturation" and "super-saturation" at
short
rotation
periods seen in coronal X-rays, or whether they continue to rise in
the
fastest rotating stars. The
saturation behavior of the different
temperature
regimes holds important clues to the organization of the surface
active
regions on these very young stars, and should allow us to distinguish
among
several competing models.
======================================================================
Proposal
Category: GO
Scientific
Category: STAR FORMATION
ID:
11117
Title:
The
Search for Atmospheric Water in the Transiting Planet HD189733b
PI:
David
Sing
PI
Institution:
CNRS,
Institut d'Astrophysique de Paris
We
propose to use the NICMOS camera to search for transit NIR signatures of
atmospheric
water in HD189733b. While water
absorption bands exist in the
optical
and IR, space-based NIR signatures are uniquely positioned to offer
the
best chance at detection. Using
narrow band photometric filters, we will
be
able to detect absorption signatures while the planet is in primary
transit. A positive detection would be the first
proof of water on an
extrasolar
planet. Furthermore, it would
provide invaluable planetary
information,
constraining the entire chemistry.
As a byproduct of the high
SNR
required for our primary science goal, we will be able to improve on the
value
of the planetary radius, a result independent of our primary science
objective. The accurate radius estimate, together
with planet structure
models,
will allow constraining the planet interior and its relationship with
formation
models and stellar metallicity.
======================================================================
Proposal
Category: GO
Scientific
Category: SOLAR SYSTEM
ID:
11118
Title:
Investigating
Near-Equinox Atmospheric Change on Uranus
PI:
Lawrence
Sromovsky
PI
Institution:
University
of Wisconsin - Madison
Uranus
is approaching its 7 December 2007 equinox, when we will be able to
observe
the entire northern hemisphere for the first time with modern cameras.
The
large seasonal phase shift expected from its long radiative time
constant
implies
that it should now exhibit nearly maximal hemispheric contrast, and
should
be in the process of reversing.
Many changes already observed, such as
the
development of the first visible-wavelength dark spot, discovered in
Cycle
15,
and the fading of the south polar cap may be indicative of the expected
reversal. We propose a detailed characterization
of Uranus' current seasonal
response
with a 7-orbit program consisting of 1 orbit of NICMOS imaging of
cloud
bands and 6 orbits of WFPC2 imaging using both broadband and narrow-band
filters
capable of tracking dark and bright discrete cloud features. Filters
between
0.467 and 1.87 microns will provide vertical sensing depths scanning
through
the pressure range where the putative methane and deeper H2S clouds
might
plausibly exist and provide strong constraints on their contributions
and
parent gas mixing ratios. These
observations have unique combinations of
spectral
range and resolution with needed temporal and spatial resolution not
available
from groundbased observations. Only HST is capable of investigating
the
Uranus dark spot.
======================================================================
Proposal
Category: GO
Scientific
Category: HOT STARS
ID:
11119
Title:
The
Stellar Origins of Supernovae
PI:
Schuyler
Van Dyk
PI
Institution:
Jet
Propulsion Laboratory
Supernovae
(SNe) have a profound effect on galaxies, and have been used
recently
as precise cosmological probes, resulting in the discovery of the
accelerating
Universe. They are clearly very
important events deserving of
intense
study. Yet, even with nearly 4000
known SNe, we know relatively
little
about the stars which give rise to these powerful explosions. The main
limitation
has been the lack of spatial resolution in pre-SN imaging data.
However,
since 1999 our team has been at the vanguard of directly identifying
SN
progenitor stars in HST images.
From this exciting new line of study, the
emerging
trend from 5 detections for Type II-Plateau SNe is that their
progenitors
appear to be relatively low mass (8 to 20 Msun) red supergiants,
although
more cases are needed.
Nonetheless, the nature of the progenitors of
Type
Ib/c SNe, a subset of which are associated with the amazing gamma-ray
bursts,
remains ambiguous. Furthermore, we
remain in the continually
embarrassing
situation that we still do not yet know which progenitor systems
explode
as Type Ia SNe, which are currently being used for precision
cosmology. We propose to confirm the identities of
the progenitors of 4 SNe
within
17 Mpc, which we expect to occur during Cycle 16, through ToO
observations
using WFPC2/PC.
======================================================================
Proposal
Category: GO
Scientific
Category: HOT STARS
ID:
11120
Title:
A
Paschen-Alpha Study of Massive Stars and the ISM in the Galactic Center
PI:
Daniel
Wang
PI
Institution:
University
of Massachusetts
The
Galactic center (GC) is a unique site for a detailed study of a
multitude
of
complex astrophysical phenomena, which may be common to nuclear regions
of
many
galaxies. Observable at resolutions unapproachable in other galaxies,
the
GC
provides an unparalleled opportunity to improve our understanding of the
interrelationships
of massive stars, young stellar clusters, warm and hot
ionized
gases, molecular clouds, large scale magnetic fields, and black holes.
We
propose the first large-scale hydrogen Paschen alpha line survey of the
GC
using
NICMOS on the Hubble Space Telescope. This survey will lead to a high
resolution
and high sensitivity map of the Paschen alpha line emission in
addition
to a map of foreground extinction, made by comparing Paschen alpha to
radio
emission. This survey of the inner 75 pc of the Galaxy will provide an
unprecedented
and complete search for sites of massive star formation. In
particular,
we will be able to (1) uncover the distribution of young massive
stars
in this region, (2) locate the surfaces of adjacent molecular clouds,
(3)
determine important physical parameters of the ionized gas, (4) identify
compact
and ultra-compact HII regions throughout the GC. When combined with
existing
Chandra and Spitzer surveys as well as a wealth of other multi-
wavelength
observations, the results will allow us to address such questions
as
where and how massive stars form, how stellar clusters are disrupted,
how
massive
stars shape and heat the surrounding medium, and how various phases of
this
medium are interspersed.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11121
Title:
Proper
Motion of the Remarkable Irradiated Jet HH399 in the Trifid Nebula
PI:
Farhad
Yusef-Zadeh
PI
Institution:
Northwestern
University
The
Trifid nebula has recently been of much interest because of its
identification
with a large number of massive protostars, as well as young
stellar
objects. HH 399 is one of the most spectacular Herbig-Haro flows
recognized
to be irradiated by the UV flux of the massive O7.5 star in the
Trifid
nebula. The irradiated jet, which is propagating in a fully ionized
medium,
contains numerous knots along the jet and also shows evidence for a
number
of isolated knots running immediately outside the jet. Two different
HST
observations of the nebula, with different scientific goals, were
carried
out
in 1997 and 2002, having sensitivities that differed by a factor of 10.
We
performed
preliminary proper motion measurements of the jet based on these
observations
and discovered a continuous velocity structure of the bright
knots
of about 230 km/sec. Here we propose four WFPC2 orbits to reobserve HH
399
in order to carry out accurate proper motion measurements over the full
extent
of the jet, based on observations spanning more than 10 years and
having
equally deep sensitivity. The proposed observations are not simply a
repeat
of previous measurements, as this will be the first highly accurate
proper
motion measurement of an irradiated jet based on two identical epochs
of
WFPC2 observations. The observations will improve the accuracy of proper
motion
measurements for HH 399 by more than a factor of five and will address
important
questions beyond our preliminary result. Currently measured velocity
differences
between the jet features are barely significant. The factor of 5
increase
in accuracy will establish the evidence for deceleration along the
jet
and the lateral motion of the jet. In addition, these measurements will
address
the kinematics of individual entrained and isolated blobs of the jet
as
it propagates into an HII region associated with the nebula. This is the
last
opportunity to perform this experiment before WFPC2 is removed from HST.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11122
Title:
Expanding
PNe: Distances and Hydro Models
PI:
Bruce
Balick
PI
Institution:
University
of Washington
We
propose to obtain repeat narrowband images of a sample of eighteen
planetary
nebulae (PNe) which have HST/WFPC2 archival data spanning time
baselines
of a decade. All of these targets
have previous high signal-to-
noise
WFPC2/PC observations and are sufficiently nearby to have readily
detectable
expansion signatures after a few years.
Our main scientific
objectives
are (a) to determine precise distances to these PNe based on their
angular
expansions, (b) to test detailed and highly successful hydrodynamic
models
that predict nebular morphologies and expansions for subsamples of
round/elliptical
and axisymmetric PNe, and (c) to monitor the proper motions
of
nebular microstructures in an effort to learn more about their physical
nature
and formation mechanisms. The proposed
observations will result in
high-precision
distances to a healthy subsample of PNe, and from this their
expansion
ages, luminosities, CSPN properties, and masses of their ionized
cores. With good distances and our hydro
models, we will be able to determine
fundamental
parameters (such as nebular and central star masses, luminosity,
age). The same images allow us to monitor the
changing overall ionization
state
and to search for the surprisingly non-homologous growth patterns to
bright
elliptical PNe of the same sort seen by Balick & Hajian (2004) in
NGC
6543. Non-uniform growth is a sure sign of
active pressure imbalances within
the
nebula that require careful hydro models to understand.
======================================================================
Proposal
Category: GO
Scientific
Category: STAR FORMATION
ID:
11123
Title:
A
NICMOS Survey for Proplyds in the RCW 38 Massive Embedded Cluster
PI:
Tyler
Bourke
PI
Institution:
Smithsonian
Institution Astrophysical Observatory
We
propose a search for line emission from photoevaporating protoplanetary
disks
in the Massive Embedded Cluster
RCW 38. These disks would be analogous
to
the "proplyds" discovered in the Orion Nebula:
disks around young low
mass
stars
which are being photoionized by a nearby O star. We
will search for
these
disks in RCW 38 using narrowband imaging in the lines of Paschen alpha
and
molecular hydrogen (1-0) S(1) with NICMOS. The
RCW 38 region is an
excellent
target for determining whether proplyds are observable
in large
numbers
outside of Orion. It is a young
embedded cluster hosting a few
hundred
low mass young stars with a large percentage showing infrared excess
indicating
the presence of disks. About 100
of these stars are found within
0.1
pc of the central O5 star, and the cluster is located within a cleared
cavity
0.2 pc in size, embedded within a
molecular cloud, exposing the
cluster
members directly to the UV radiation from the O star.
Unlike Orion,
but
like many other young clusters, RCW 38 is not seen in visible light, and
infrared
imaging is needed. The best line
in the infrared for revealing
proplyds
is the Paschen alpha line, which is not detectable from the ground.
Only
HST is able to perform these observations. From
these observations we
will
estimate the lifetime of the evaporating disks, and ascertain whether
these
disks will survive long enough to form planets.
======================================================================
Proposal
Category: GO
Scientific
Category: QUASAR ABSORPTION LINES AND IGM
ID:
11124
Title:
The
Origin of QSO Absorption Lines from QSOs
PI:
David
Bowen
PI
Institution:
Princeton
University
We
propose using WFPC2 to image the fields of 10 redshift z ~ 0.7
foreground
(FG)
QSOs which lie within ~29-151 kpc of the sightlines to high-z background
(BG)
QSOs. A surprisingly high fraction of the BG QSO spectra show strong
MgII
(2796,2803)
absorption lines at precisely the same redshifts as the FG QSOs.
The
high resolution capabilities of WFPC2 are needed to understand the
origin
of
these absorption systems, in two ways.
First, we wish to explore the FG
QSO
environment as close as possible to the position of the BG QSO, to
search
for
interloping group or cluster galaxies which might be responsible for the
absorption,
or irregularly shaped post-merger debris between the FG and BG QSO
which
may indicate the presence of large amount of disrupted gas along a
sightline.
Similarly, high resolution images are needed to search for signs of
tidal
interactions between any galaxies which might be found close to the FG
QSO.
Such features might provide evidence of young merging events causing the
start
of QSO duty cycles and producing outflows from the central AGN. Such
winds
may be responsible for the observed absorption lines.
Second, we seek
to
measure the intrinsic parameters of the FG QSO host galaxy, such as
luminosity
and morphology, to correlate with the properties of the MgII
absorption
lines. We wish to observe each
field through the F814W filter,
close
to the rest-frame B-band of the FG QSO. These blue data can reveal
enhanced
star formation regions close to the nucleus of the host galaxy, which
may
be indicative of galaxy mergers with the FG QSO host. The FG QSO
environment
offers quite a different set of phenomena which might be
responsible
for MgII absorption, providing an important comparison to studies
of
MgII absorption from regular field galaxies.
======================================================================
Proposal
Category: GO
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11125
Title:
The
Dynamical Evolution of Globular Clusters
PI:
Joel
Bregman
PI
Institution:
University
of Michigan
Globular
clusters evolve through dynamical interactions, with primordial
binaries
extending the time until core collapse by up to an order of
magnitude,
depending on the initial binary fraction.
These dynamical
interactions
plus mass segregation causes the binary fraction to rise in the
core
but fall at larger radii. We hope
to eventually test these broad
predictions
by comparing them to the binary properties for globular clusters
at
different states of evolution, defined by the ratio of their age to the
dynamical
relaxation time at the half-light radius.
The most important
unknown
aspects in the modeling process are the initial conditions of binaries
in
the cluster. Here we propose to
determine the initial binary fraction as a
function
of radius by studying three of the dynamically youngest globular
clusters
(NGC 5053, NGC 5466, and NGC 5897).
The presence of binaries
thickens
the Main Sequence in a color-magnitude diagram, which can be detected
with
deep multicolor images.
======================================================================
Proposal
Category: GO
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11126
Title:
Resolving
the Smallest Galaxies
PI:
Kristin
Chiboucas
PI
Institution:
University
of Hawaii
An
order of magnitude more dwarf galaxies are expected to inhabit the Local
Group,
based on currently accepted galaxy formation models, than have been
observed. This discrepancy has been noted in
environments ranging from the
field
to rich clusters, with evidence emerging that lower density regions
contain
fewer dwarfs per giant than higher density regions, in further
contrast
to model predictions. One possible
explanation for this involves the
effects
of reionization on the forming galaxies and naturally explains both
the
dearth of dwarf galaxies and the apparent environmental dependence.
However,
before such theories can be fully tested, we require a better
understanding
of the distribution of dwarf galaxies. Currently, there is no
complete
census of the faintest dwarf galaxies in any environment.
The
discovery
of the smallest and faintest dwarfs is hampered by the limitations
in
detecting such faint and low surface brightness galaxies, and this is
compounded
by the great difficulty in determining accurate distances to, or
ascertaining
group membership for, such faint objects.
The M81 group provides
a
unique means for establishing membership for galaxies in a low density
region
complete to magnitudes as faint as M_R ~ -7. With
a distance modulus
of
27.8, the tip of the red giant branch (TRGB) appears at I ~ 24, just
within
the
reach of ground based surveys. We
currently have surveyed a 30 square
degree
region around M81 with the CFHT/Megacam.
From these images we have
detected
15 new candidate dwarf galaxies.
We propose to use the HST with
WFPC2
to image these 15 galaxies in F606W and F814W bands in order to
construct
a color-magnitude diagram down to I = 25.5 from which to measure
accurate
TRGB distances to these candidate galaxies and determine star
formation
and metallicity histories. The
overall project will provide a
survey
of the dwarf galaxies in the M81 group environment with unprecedented
completeness
to a limit of M_R < -7.
======================================================================
Proposal
Category: GO
Scientific
Category: HOT STARS
ID:
11127
Title:
Mapping
the nebula surrounding the enigmatic X-ray source at the center of the
Vela Jr
SNR
PI:
Andrea
De Luca
PI
Institution:
CNR,
Istituto di Astrofisica Spaziale
A
compact X-ray source, showing nothing but steady unpulsed thermal
emission,
lies
close to the center of the young and nearby supernova remnant dubbed
"Vela
Jr". It is a typical member of a class of enigmatic sources, supposed to
be
the youngest members of the radio-quiet neutron star family. Quite
surprisingly,
we discovered in ground-based optical observations a small
Halpha
nebula spatially coincident with the X-ray source. Such a nebula
potentially
carries very important information on the nature of the X-ray
source,
which remains elusive in spite of large observational efforts. We
propose
to use the WFPC2 to collect high
resolution Halpha images of the
nebula
in order to resolve its structure, to understand its nature, and to
identify
its connection with the X-ray source. Addressing all these points
will
also have important implications for our interpretation of the compact
X-
ray
source and on of other objects of the same class.
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11128
Title:
Time
Scales Of Bulge Formation In Nearby Galaxies
PI:
David
Fisher
PI
Institution:
University
of Texas at Austin
Traditionally,
bulges are thought to fit well into galaxy formation models of
hierarchical
merging. However, it is now becoming well established that many
bulges
formed through internal, secular evolution of the disk rather than
through
mergers. We call these objects pseudobulges. Much
is still unknown
about
pseudobulges, the most pressing questions being:
How, exactly, do they
build
up their mass? How long does it take? And, how many exist?
We are after
an
answer to these questions. If pseudobulges form and evolve over longer
periods
than the time between mergers, then a significant population of
pseudobulges
is hard to explain within current galaxy formation theories. A
pseudobulge
indicates that a galaxy has most likely not undergone a major
merger
since the formation of the disk. The ages of pseudobulges give us an
estimate
for the time scale of this quiescent evolution. We propose to use
21.4
orbits of HST time to complete UBVIH imaging on a sample of 33 nearby
galaxies
that we have observed with Spitzer in the mid-IR. These data will be
used
to measure spatially resolved stellar population parameters (mean
stellar
age,
metallicity, and star formation history); comparing ages to star
formation
rates allows us to accurately constrain the time scale of
pseudobulge
formation. Our sample of bulges
includes both pseudo- and
classical
bulges, and evenly samples barred and unbarred galaxies. Most of our
sample
is imaged, 13 have complete UBVIH coverage; we merely ask to complete
missing
observations so that we may construct a uniform sample for studying
bulge
formation. We also wish to compare
the stellar population parameters to
a
variety of bulge and global galaxy properties including star formation
rates,
dynamics, internal bulge morphology, structure from bulge-disk
decompositions,
and gas content. Much of this data set is already or is being
assembled.
This will allow us to derive methods of pseudobulge identification
that
can be used to accurately count pseudobulges in large surveys. Aside
from
our
own science goals, we will present this broad set of data to the
community. Thus, we waive proprietary periods for
all observations.
======================================================================
Proposal
Category: GO
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11129
Title:
The
Star Formation History of the Fornax Dwarf Spheroidal Galaxy
PI:
Enrico
Held
PI
Institution:
Osservatorio
Astronomico di Padova
The
Fornax dwarf spheroidal galaxy is one of the most luminous dwarf
satellites
of the Milky Way. It is unusual in
many ways:
it
hosts 5 globular
clusters,
shows some relatively young stars, and has faint sub-structures
which
have been interpreted as signs of recent interactions.
It is thus of
great
interest to learn the complete star formation history (SFH) of Fornax to
establish
a link between its evolutionary path and the predictions from
numerical
simulations, as a test of our understanding of dwarf galaxy
evolution.
Yet many questions remain open. Is
the old stellar population made
up
of stars formed in a very early burst, perhaps before the epoch of
reionisation,
or the result of a more continuous star formation between 13 and
9
Gyr ago ? How quickly did Fornax increase its metallicity during its
initial
assembly
and during subsequent episodes of star formation ?
Are accretion
episodes
required to explain the age-metallicity history of Fornax ? However,
there
has never been a comprehensive study of the global SFH of the Fornax
field
based on data of sufficient depth to unambiguously measure the age
mixture
of the stellar populations and their spatial variation. We propose to
use
the WFPC2 to obtain very deep images in several fields across the
central
region
of Fornax in order to reach the oldest main-sequence turnoffs. The
number
of fields is determined by the need to measure the SFH over different
regions
with distinct kinematics and metallicity.
The resolution achievable
with
HST is crucial to answer these questions because, to derive the age
distribution
of the oldest stars, we are interested in I magnitude differences
of
the order 0.2 mag in crowded fields at V=24.5. We
will directly measure
the
time variation in star-formation rate over the entire galaxy history,
from
first
stars coeval with the Milky Way halo to the youngest populations 200 Myr
ago.
The combination of detailed CMD analysis with WFPC2 with our existing
metallicity
and kinematic information will allow us to trace out the early
phases
of its evolution.
======================================================================
Proposal
Category: GO
Scientific
Category: AGN/QUASARS
ID:
11130
Title:
AGNs
with Intermediate-mass Black Holes: Testing the Black Hole-Bulge
Paradigm, Part
II
PI:
Luis
Ho
PI
Institution:
Carnegie
Institution of Washington
The
recent progress in the study of central black holes in galactic nuclei
has
led
to a general consensus that supermassive (10^6-10^9 solar mass) black
holes
are closely connected with the formation and evolutionary history of
large
galaxies, especially their bulge component. Two
outstanding issues,
however,
remain unresolved. Can central
black holes form in the absence of a
bulge? And does the mass function of central
black holes extend below 10^6
solar
masses? Intermediate-mass black
holes (<10^6 solar masses), if they
exist,
may offer important clues to the nature of the seeds of supermassive
black
holes. Using the SDSS, our group
has successfully uncovered a new
population
of AGNs with intermediate-mass black holes that reside in low-
luminosity
galaxies. However, very little is
known about the detailed
morphologies
or structural parameters of the host galaxies themselves,
including
the crucial question of whether they have bulges or not.
Surprisingly,
the majority of the targets of our Cycle 14 pilot program have
structural
properties similar to dwarf elliptical galaxies. The
statistics
from
this initial study, however, are really too sparse to reach definitive
conclusions
on this important new class of black holes. We
wish to extend
this
study to a larger sample, by using the Survey mode to obtain WFPC2 F814W
images
of 85 (from a parent sample of 175) AGNs with intermediate-mass black
holes
selected from our final SDSS search.
We are particularly keen to
determine
whether the hosts contain bulges, and if so, how the fundamental
plane
properties of the host depend on the mass of their central black holes.
We
will also investigate the environment of this unique class of AGNs.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM IN EXTERNAL GALAXIES
ID:
11131
Title:
Star
formation at large radii in cooling flow brightest cluster galaxies
PI:
Walter
Jaffe
PI
Institution:
Sterrewacht
Leiden
We
propose to take deep ACS FUV images of the bright central galaxies in
two
powerful
cooling flow clusters for which we have VLT UBR images, with the
object
of determining whether the UV excesses we observe at large radii
(>15kpc)
are caused by young stars, ultrahot (WR) stars, or an as yet unknown
source. Current models of excess UV light at
the AGN-dominated centers of
these
galaxies cannot easily be extended to large radii.
New understanding of
star
formation in these clusters will be directly applicable to scenarios of
galaxy
formation in the early universe.
======================================================================
Proposal
Category: GO
Scientific
Category: COOL STARS
ID:
11132
Title:
Constraining
the age of the AB Dor system
PI:
Markus
Janson
PI
Institution:
Max-Planck-Institut
fur Astronomie, Heidelberg
The
zero-age main sequence K-type star AB Dor, with an age of 25 to 125 Myr,
is
the most active young star in the solar neighbourhood. It is part of a
quadruple
system of young stars. The mass of AB Dor C, the
closest and lowest
mass
companion, has been derived from
astrometric observations (with the VLA
and
adaptive optics at the VLT) to
94+-3 times the mass of Jupiter. The low
mass
(close to the hydrogen burning limit) combined with the young age makes
AB
Dor C a unique calibration source for evolutionary tracks for very
low-mass
stars
and brown dwarfs, provided that a precise age estimate can be derived
for
the system. We propose to use the HST planetary camera to obtain
resolved
component
photometry of the M-type pre-main sequence star AB Dor Ba
and Bb in
order
to derive individual spectral types and luminosities, which will enable
us
to age-date the AB Dor system to better than +-20 Myr. In addition, the
observations
will help to constrain the Ba/Bb orbit, and hence to derive
dynamical
mass estimates as well.
======================================================================
Proposal
Category: GO
Scientific
Category: HOT STARS
ID:
11133
Title:
Late-Time
Photometry of SN 2005hk: A New Kind of Type Ia Supernova
PI:
Saurabh
Jha
PI
Institution:
Rutgers
the State University of New Jersey
Our
lack of understanding of Type Ia supernova (SN Ia) explosions limits our
confidence
in their use for cosmology. While
there is broad agreement that
these
objects represent the explosions of white dwarfs, the details of the
explosion
mechanism are not well-understood.
Recent observations have
detected
a previously unacknowledged variant class of SNe Ia whose photometric
and
spectroscopic peculiarities make them quite distinct from normal SNe Ia.
These
objects represent a challenge for thermonuclear supernova models, as a
complete
theory of exploding white dwarfs must allow for their existence. A
particularly
well-studied example of this class of objects is the recent SN
2005hk,
whose properties in some respects resemble those of models which
invoke
a subsonic burning front, called a deflagration. We
propose to test SN
Ia
models by obtaining late-time photometry for this extreme SN Ia using
WFPC2
and
NICMOS on HST. We will accurately
measure the late-time photometric
decline
rate and spectral energy distribution (SED). These
observations will
allow
us to test whether the ejecta contain the large amount of oxygen
predicted
by certain models, the efficiency of energy deposition by gamma rays
and
positrons, and possibly detect major evolution of the SED expected due
to
a
change in the dominant cooling mechanism of the ejecta.
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11134
Title:
WFPC2
Tidal Tail Survey: Probing Star
Cluster Formation on the Edge
PI:
Karen
Knierman
PI
Institution:
University
of Arizona
The
spectacular HST images of the interiors of merging galaxies such as the
Antennae
and NGC 7252 have revealed rich and diverse populations of star
clusters
created over the course of the interaction. Intriguingly,
our WFPC2
study
of tidal tails in these and other interacting pairs has shown that star
cluster
birth in the tails does not follow a similarly straightforward
evolution. In fact, cluster formation in these
relatively sparse environments
is
not guaranteed -- only one of six tails in our initial study showed
evidence
for a significant population of young star clusters.
The tail
environment
thus offers the opportunity to probe star cluster formation on the
edge
of the physical parameter space (e.g., of stellar and gas mass, density,
and
pressure) that permits it to occur.
We propose to signficantly extend our
pilot
sample of optically bright, gas-rich tidal tails by a factor of 4 in
number
to include a more diverse population of tails, encompassing major and
minor
mergers, gas-rich and gas-poor tails, as well as early, late, and merged
interaction
stages. With 21 orbits of HST WFPC2 imaging in the F606W and F814W
filters,
we can identify, roughly age-date, and measure sizes of star clusters
to
determine what physical parameters affect star cluster formation. WFPC2
imaging
has been used effectively in our initial study of four mergers, and it
will
be possible in this program to reach similar limits of Mv=-8.5 for each
of
16 more tails. With the much
larger sample we expect to isolate which
factors,
such as merger stage, HI content, and merger mass ratio, drive the
formation
of star clusters.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11135
Title:
Extreme
makeovers: Tracing the transformation of massive galaxies at z~2.5
PI:
Mariska
Kriek
PI
Institution:
Universiteit
Leiden
To
obtain a full spectroscopic census of the universe at z~2.5 we have
conducted
a near-infrared spectroscopic survey for K-selected galaxies. We
found
that, in contrast to the local universe, massive high-redshift galaxies
span
a wide range of properties, varying from (dusty) star burst to "red and
dead"
galaxies. This may imply that massive galaxies transform from star-
forming
to quiescent galaxies in the targeted redshift range. To understand
whether
the 9 quiescent galaxies in our sample are the progenitors of local
elliptical,
we are observing them in the current cycle with NIC2.
For cycle
16
we propose to complete our sample of massive z~2.5 galaxies and image
the
remaining
10 galaxies, which all have emission lines. Based on emission-line
diagnostics,
6 of these galaxies are identified as star-forming objects and 4
harbor
an active galactic nucleus. The goals are to 1) determine whether star
formation
in massive z~2.5 galaxies takes place in disks or is triggered by
merger
activity, 2) derive the contribution of AGNs to the rest-frame optical
emission,
and 3) test whether the morphologies are consistent with the idea
that
the star-forming galaxies, AGNs, and quiescent galaxies represent
subsequent
phases of an evolutionary sequence. The combination of both
programs
will provide the first morphological study of a spectroscopically
confirmed
massive galaxy sample at z~2.5.
======================================================================
Proposal
Category: GO
Scientific
Category: COOL STARS
ID:
11136
Title:
Resolving
Ultracool Astrophysics with Brown Dwarf Binaries
PI:
Michael
Liu
PI
Institution:
University
of Hawaii
We
propose to obtain resolved far-red and near-IR photometry of 14 brown
dwarf
binaries
with HST/NICMOS in order to study one of the long-standing puzzles in
ultracool
astrophysics, namely the rapid change in spectra from L dwarfs to T
dwarfs
at nearly constant effective temperature (a.k.a. the ``L/T
transition''). While many nearby brown dwarfs have
been studied, use of such
samples
is inevitably hindered by the unknown ages, masses, and metallicities
of
the field population.
Characterization of resolved ultracool binaries is a
promising
avenue for addressing this problem, by providing coeval systems of
the
same composition with comparable masses and temperatures.
Our proposed
HST/NICMOS
(0.9-1.6 micron) observations will be combined with longer
wavelength
ground-based photometry and spectroscopy from Keck laser guide star
adaptive
optics. The resulting multi-band
(0.9-2.5 micron) dataset will be a
unique
resource for measuring the evolution of spectral energy distributions
across
the L/T transition, to test state-of-the-art atmospheric models, and to
determine
the physical process(es) that dominate the L/T transition.
Understanding
the L/T transition is important not only for testing brown dwarf
atmospheres,
but also provides a key pathway for understanding the same
physical
effects, namely the formation and removal of clouds, in the
atmospheres
of the extrasolar planets.
======================================================================
Proposal
Category: GO
Scientific
Category: HOT STARS
ID:
11137
Title:
First
Accurate Geometric Distance to a Galactic Wolf-Rayet Star: Knots in the
Ejecta
M1-67
PI:
Anthony
Moffat
PI
Institution:
Universite
de Montreal
M
1-67 is the youngest known ejection nebula surrounding a Population I
Wolf-
Rayet
star, in this case the WN8 star WR 124.
Our deep H-alpha HST/WFPC2
image
of this object in March 1997 revealed, for the first time in such a
nebula,
numerous bright, mostly unresolved knots (typical diameters 0.1-0.2")
often
surrounded by what appear to be their own local spherical diffuse 'wind'
bubbles.
We propose to obtain a second epoch H-alpha image of M 1-67,
essentially
repeating the Epoch1 instrumental set-up. By measuring the proper
motions
of the knots, we will derive a
relatively precise and assumption-free
geometric
distance (thus also a luminosity)
to a Galactic Wolf-Rayet
star,
the
first of its kind. This will help to confirm the suspected runaway
status
of
WR 124 and shed new light on the nature of progenitors of
gamma-ray
bursts.
Moreover, we intend to document and measure the anticipated
morphology/brightness
changes in the fine-stucture features of the nebula over
the
11-year interval, as they relate to wind-embedded shocks. This will
provide
important input for interaction models of a stellar wind with
circumstellar
matter.
======================================================================
Proposal
Category: GO
Scientific
Category: AGN/QUASARS
ID:
11138
Title:
The
Physics of the Jets of Powerful Radio Galaxies and Quasars
PI:
Eric
Perlman
PI
Institution:
Florida
Institute of Technology
We
propose to obtain HST polarimetry of the jets of the quasars 1150+497
and
PKS
1136-135. Our goal is to solve the
riddle of their high-energy emission
mechanism,
and tackle issues such as particle acceleration and jet dynamics.
Our
targets are the optically brightest quasar jets, and they span the range
of
luminosities and beaming parameters seen in these objects.
Recent
observations
with Spitzer, HST and Chandra have shed new light on the spectral
morphology
of quasar jets, throwing wide open the question of the nature of
their
optical and X-ray emission. Three
mechanisms are possible, including
synchrotron
emission as well as two Comptonization processes. Polarimetry
can
uniquely
determine which of these mechanisms operates in the optical. We will
compare
the optical polarimetry to in-hand radio polarimetry as well as in-
hand
and new Spitzer, HST and Chandra imaging to gain new insights on the
structure
of these jets, as well as particle acceleration mechanisms and jet
dynamics.
======================================================================
Proposal
Category: GO
Scientific
Category: HOT STARS
ID:
11139
Title:
NICMOS
Observations of the Microquasar GRS 1758-258
PI:
Ian
Smith
PI
Institution:
Rice
University
The
galactic black hole candidate GRS 1758-258 is normally one of the
brightest
persistent gamma-ray sources in the vicinity of the galactic center.
It
is a microquasar with relativistic radio jets emanating from a central
variable
source. Microquasars are excellent
nearby test laboratories for
studying
the complex accretion and outflow processes that take place near
black
hole horizons. Despite an accurate
location provided by Chandra and the
VLA
and over a decade of careful ground-based studies, the optical/infrared
counterpart
to GRS 1758-258 remains unknown. A stellar counterpart is
expected,
but the current candidates are all more than 2 sigma from the center
of
the error circle. The ground-based
infrared flux limits are also right at
the
values expected for the synchrotron emission from the outflow from the
black
hole, and possibly for the emission from the accretion disk. This leaves
open
the question as to what is powering this very energetic persistent
source. Here we propose to use NICMOS to
perform broad-band imaging of the
GRS
1758-258 error box. These images
will be more than three magnitudes more
sensitive
than the current ground-based ones. The resulting spectra will
reveal
the thermal/non-thermal nature of the sources in the region of the
error
box, and the high spatial resolution images may reveal a jet structure.
We
propose to perform three visits of two orbits each spanning the
suggested
18.45
day binary orbital period of the system: a
correct counterpart
identification
should be confirmed by its variability.
We will also aim to
support
the HST observations with X- and gamma-ray observations using Swift or
INTEGRAL,
and with longer wavelength observations from the ground.
======================================================================
Proposal
Category: GO
Scientific
Category: HOT STARS
ID:
11140
Title:
Can
mass-ejections from late He-shell flash stars constrain
convective/reactive
flow modeling of stellar interiors?
PI:
Klaus
Werner
PI
Institution:
Universitat
Tubingen, Institut fur Astronomie & Astrophysik
The
existence of H-deficient knots around the central stars of the planetary
nebulae
Abell 30 and Abell 78 is still unexplained. We hypothesize that these
knots
were ejected during a very late helium-shell flash (= very late thermal
pulse,
VLTP) suffered by the precursor white dwarf stars. If this is true,
then
the characteristics of these knots (mass, velocity, density, spatial
distribution)
allow to draw conclusions on the course of the hydrogen-
ingestion
flash detonation that is triggered by the He-shell flash. This
provides
important, otherwise inaccessible constraints for the hydrodynamical
modeling
of convective/reactive flows in stellar interiors. Understanding the
physics
of these flows is not only important for the understanding of these
particular
central stars, but also for the frequent, very similar
convective/reactive
events that determine the nucleosynthesis in Pop. III
stars. With this proposal we want to proof or
discard the idea that the H-
deficient
knots are resulting from a VLTP. If true, then they can be exploited
for
flash-physics diagnostics. We propose a simple test. We search for such
knots
around five H-deficient central stars (PG1159 stars). Our models
predict,
that only those stars with residual nitrogen in the atmosphere have
suffered
a VLTP and, hence, should have expelled knots. We therefore want to
take
[O III] images of stars which have photospheric N and those which do
not.
======================================================================
Proposal
Category: GO
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11141
Title:
White
dwarfs in the open star cluster NGC 188
PI:
Kurtis
Williams
PI
Institution:
University
of Texas at Austin
White
dwarf cooling sequences represent the only ways in which we can
determine
ages of Galactic components such as the disk and the halo, and they
are
an independent check on main sequence ages of globular
star clusters.
These
age measurements rely heavily on theoretical cooling models, many of
which
disagree by as much as a few gigayears for the coolest white dwarfs.
Further,
observations of the white dwarf sequence in the super metal-rich open
cluster
NGC 6791 have found a white dwarf age several gigayears younger than
the
accepted cluster age determined by main-sequence fitting.
The white dwarf
sequence
of the solar-metallicity, 7-Gyr old open cluster NGC 188 can provide
some
much-needed insight into these uncertainties, but previous HST
observations
were too shallow to detect the oldest, faintest white dwarfs in
the
cluster. We propose deep imaging
of two fields at the center of the
cluster
with the following goals: (1)
To detect the end of the white dwarf
cooling
sequence, providing a much-needed empirical data point for cool white
dwarf
evolutionary models, (2) to compare the white dwarf luminosity function
of
NGC 188 with that of NGC 6791 to determine if the odd white dwarf
sequence
in
the latter cluster is due to the cluster's high metallicity or due to a
shortcoming
in theoretical models, and (3) to determine via photometry the
masses
of white dwarfs formed by solar-mass stars, a quantity not yet
empirically
measured.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM IN EXTERNAL GALAXIES
ID:
11142
Title:
Revealing
the Physical Nature of Infrared Luminous Galaxies at 0.3<z<2.7
Using HST
and Spitzer
PI:
Lin
Yan
PI
Institution:
California
Institute of Technology
We
aim to determine physical properties of IR luminous galaxies at
0.3<z<2.7
by
requesting coordinated HST/NIC2 and MIPS 70um observations of a unique,
24um
flux-limited sample with complete Spitzer mid-IR spectroscopy. The 150
sources
investigated in this program have S(24um) > 0.8mJy and their mid-IR
spectra
have already provided the majority targets with spectroscopic
redshifts
(0.3<z<2.7). The proposed 150~orbits of NIC2 and 66~hours of MIPS
70um
will provide the physical measurements of the light distribution at the
rest-frame
~8000A and better estimates of the bolometric luminosity. Combining
these
parameters together with the rich suite of spectral diagnostics from the
mid-IR
spectra, we will (1) measure how common mergers are among LIRGs and
ULIRGs
at 0.3<z<2.7, and establish if major mergers are the drivers of
z>1
ULIRGs,
as in the local Universe. (2) study the co-evolution of star formation
and
blackhole accretion by investigating the relations between the fraction
of
starburst/AGN
measured from mid-IR spectra vs. HST morphologies, L(bol) and z.
(3)
obtain the current best estimates of the far-IR emission, thus L(bol)
for
this
sample, and establish if the relative contribtuion of mid-to-far IR dust
emission
is correlated with morphology (resolved vs. unresolved).
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11143
Title:
NICMOS
imaging of submillimeter galaxies with CO and PAH redshifts
PI:
Andrew
Baker
PI
Institution:
Rutgers
the State University of New Jersey
We
propose to obtain F110W and F160W imaging of 10 z~2.4 submillimeter
galaxies
(SMGs) whose optical redshifts have been confirmed by the detection
of
millimeter CO and/or mid-infrared PAH emission. With
the 4000A break
falling
within/between the two imaging filters, we will be able to study these
sources'
spatially resolved stellar populations (modulo extinction) in the
rest-frame
optical. SMGs' large luminosities
appear to be due largely to
merger-triggered
starbursts; high-resolution NICMOS imaging will help us
understand
the stellar masses, mass ratios, and other properties of the merger
progenitors,
valuable information in the effort to model the mass assembly
history
of the universe.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11144
Title:
Building
on the Significant NICMOS Investment in GOODS: A Bright, Wide-Area
Search for
z>=7 Galaxies
PI:
Rychard
Bouwens
PI
Institution:
University
of California - Santa Cruz
One
of the most exciting frontiers in observational cosmology has been to
trace
the buildup and evolution of galaxies from very early times. While
hierarchical
theory teaches us that star formation in galaxies likely starts
out
small and builds up gradually, only recently has it been possible to see
evidence
for this observationally through the evolution of the LF from z~6 to
z~3. Establishing that this build up occurs
from even earlier times (z~7-8)
has
been difficult, however, due to the small size of current high-redshift
z~7-8
samples -- now numbering in the range of
~4-10 sources. Expanding
the
size
of these samples is paramount, if we are to push current studies of
galaxy
buildup back to even earlier times.
Fortunately, we should soon be
able
to do so, thanks to ~50 arcmin**2 of deep (26.9 AB mag at 5 sigma)
NICMOS
1.6
micron data that will be available over the two ACS GOODS fields as a
result
of one recent 180-orbit ACS backup program and a smaller program.
These
data will nearly triple the deep near-IR imaging currently available
over
these fields and therefore represent a significant resource for finding
and
characterizing the brightest and likely most massive high-redshift
sources
(which
can be found in no other way but with wide-area searches).
To make
maximal
use of these data, we will first isolate a small sample of the most
interesting,
candidate z>=7 galaxies from this survey through their z-H
colours. We then propose to follow-up each
of these candidates with NICMOS
imaging
at 1.1 microns ('J'-band) to determine which of these sources are at
z>=7
and thus significantly expand our sample of luminous, z>=7 galaxies.
Since
preliminary studies indicate that these candidates occur in only 30% of
the
NIC3 fields, our follow-up strategy is ~3 times as efficient as without
this
preselection and 9 times as efficient as a search in a field with no
pre-
existing
data. We expect to identify ~8
luminous z-dropouts and possibly ~2
z~10
J-dropouts as a result of this program, more than tripling the number
currently
known. The increased sample sizes
are important if we are to
solidify
current conclusions about galaxy buildup and the evolution of the LF
from
z~8. In addition to the high
redshift science, these deep 1.1 micron
data
would have significant value for many diverse endeavors, including (1)
improving
our constraints on the stellar mass density at z~7-10 and (2)
doubling
the number of galaxies at z~6 for which we can estimate dust
obscuration.
======================================================================
Proposal
Category: GO
Scientific
Category: STAR FORMATION
ID:
11145
Title:
Probing
the Planet Forming Region of T Tauri Stars in Chamaeleon
PI:
Nuria
Calvet
PI
Institution:
University
of Michigan
By
studying the inner, planet-forming regions of circumstellar disks around
low-mass
pre-main sequence stars we can refine theories of giant planet
formation
and develop timescales for the evolution of disks and their planets.
Spitzer
infrared observations of T Tauri stars in the Chamaeleon star-forming
region
have given us an unprecedented look at dust evolution in young objects.
However,
despite this ground breaking progress in studying the dust in young
disks,
the gas properties of the inner disk remain essentially unknown. Using
ACS
on HST, we propose to measure the H_2
emission originating in the
innermost
disk regions of classical T Tauri stars in different stages of
evolution
with the objective of revealing the timescales of gas dissipation
and
its relationship to dust evolution.
This proposal is part of a
comprehensive
effort with approved programs on Spitzer, Gemini, and Magellan
that
aim to characterize the state of gas and dust in disks where planets may
already
have formed.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM IN EXTERNAL GALAXIES
ID:
11146
Title:
The
Role of Stellar Feedback in Galaxy Evolution
PI:
Daniela
Calzetti
PI
Institution:
University
of Massachusetts
Stellar
feedback - the return of mass and energy from star formation to the
interstellar
medium - is one of the primary engines of galaxy evolution. Yet,
the
observational canvass of feedback is incomplete. We propose to
investigate
this
fundamental aspect of star formation on one local actively star-forming
galaxy,
He2-10, selected to occupy an
unexplored niche in the key parameter
space
of stellar mass. The WFPC2
narrow-band observations in the light of H-
beta,
[OIII], H-alpha, and [SII] will: (1)
discriminate the feedback-induced
shock
fronts from the photoionized regions; (2) map, and provide a complete
census
of, the shocks inside and around the starburst regions; and (3) measure
the
energy budget of the star-formation-produced shocks. These observations,
joined
by our previous data and studies on starbursts, will yield: (1) the
efficiency
of the feedback, i.e. the fraction of the star formation's
mechanical
energy transported out of the starburst volume rather than radiated
away,
in the dual-parameter space of host's stellar mass and star formation
intensity;
(2) the conditions under which feedback morphs from a localized
process
to a galactic scale mechanism. The high angular resolution of HST is
crucial
for separating the spatially narrow shock fronts (~10 pc=0.2" at 10
Mpc)
from the more extended photoionization fronts. This project will provide
the
most comprehensive quantitative foundation of stellar feedback and a
gauge
for
determining the role of feedback in the energetics, structure and star
formation
history of galaxies.
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11147
Title:
The
Origin of Diffuse UV Light from Spiral Disks
PI:
Rupali
Chandar
PI
Institution:
Carnegie
Institution of Washington
The
ultraviolet light from galaxies has been used as a beacon for tracing
the
cosmic
star formation history of the Universe, yet we have an incomplete
understandingof
many characteristics of this light.
Most of the UV emission
from
nearby, normal star--forming galaxies is unresolved and "diffuse",
and
GALEX
has shown that in spiral disks it permeates the inter-arm regions. The
nature
of this diffuse inter-arm component is under debate.
Recent results
suggest
that it may arise from non-ionizing UV photons which originate in star
forming
regions in the spiral arms, travel in the plane of the galaxy, and
then
scatter off of diffusely distributed cold dust grains.
Alternatively, an
in-situ,
unresolved stellar population could produce the observed inter-arm UV
emission. This project seeks to establish which
of the two competing
scenarios
is responsible for the bulk of this diffuse emission.
We propose to
use
HST's UV imaging capability (ACS/SBC) to obtain deep observations of
selected
fields in the nearby spiral galaxy M101, for which available (low
angular
resolution) data favor the 'scattered light' scenario.
Our
observations
are designed to detect any faint, UV-luminous stellar population
down
to main sequence B5 stars. With
these data, we will establish the nature
of
the bulk of the diffuse UV light in this spiral galaxy by:
(i)
quantifying
the
contribution from dust-scattered light; (ii) measuring the contribution
to
the
ubiquitous diffuse ionized medium from in-situ ionizing stars; and (iii)
providing
constraints on the observed stellar mass function in the field.
Only
HST has the UV sensitivity and angular resolution to discriminate
in-situ
stellar
populations from scattered light.
The ultimate goal of this project
is
to re-'calibrate' the UV emission as a star formation rate indicator,
which
will
need to account for any scattered component.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11148
Title:
High
Contrast Imaging of Dusty White Dwarfs
PI:
John
Debes
PI
Institution:
Carnegie
Institution of Washington
For
the past 18 years, only one white dwarf with a circumstellar dust disk
was
known
to exist. In the last two years,
six new disks have been discovered.
Since
all material inwards of a few AU should be scoured clean during post
main
sequence evolution, the primary explanation is the presence of a
planetary
system that is perturbing relic planetesimals into the tidal
disruption
radius of the white dwarf. Dusty
disks around white dwarfs should
be
markers for planets and we propose to use high contrast imaging to
search
for
faint companions down to 6 M_$J$ that may be feeding the disks. White
dwarfs
are uniquely suited for planet searches, where the planet/white dwarf
contrast
is less than for main sequence stars.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11149
Title:
Characterizing
the Stellar Populations in Lyman-Alpha Emitters and Lyman Break
Galaxies at
5.7<z<7 in the Subaru Deep Field
PI:
Eiichi
Egami
PI
Institution:
University
of Arizona
The
epoch of reionization marks a major phase transition of the Universe,
during
which the intergalactic space became transparent to UV photons.
Determining
when this occurred and the physical processes involved represents
the
latest frontier in observational cosmology. Over the last few years,
searches
have intensified to identify the population of high-redshift (z>6)
galaxies
that might be responsible for this process, but the progress is
hampered
partly by the difficulty of obtaining physical information (stellar
mass,
age, star formation rate/history) for individual sources. This is
because
the number of z>6 galaxies that have both secure spectroscopic
redshifts
and high-quality infrared photometry (especially with Spitzer/IRAC)
is
still fairly small. Considering that only several photometric points are
available
per source, and that many model SEDs are highly degenerate, it is
crucial
to obtain as many observational constraints as possible for each
source
to ensure the validity of SED modeling. To better understand the
physical
properties of high-redshift galaxies, we propose here to conduct
HST/NICMOS
(72 orbits) and Spitzer/IRAC (102 hours) imaging of
spectroscopically
confirmed, bright (z<26 mag (AB)) Ly-alpha emitters (LAEs)
and
Lyman-break galaxies (LBGs) at 5.7<z<7 selected from the Subaru
Deep
Field.
Spectroscopic redshifts remove one critical free parameter from SED
modeling
while bright source magnitudes ensure high-quality photometric data.
By
making accurate determinations of stellar masses, ages, and
star-formation
histories,
we will specifically address the following major questions: (1)
Do
LAEs
and LBGs represent physically different galaxy populations at z>6 as
suggested
recently? (2) Is Ly-alpha emission systematically suppressed at z>6
with
respect to continuum emission? (i.e., are we reaching the epoch of
incomplete
reionization?), and (3) Do we see any sign of abnormally young
stellar
population in any of the z>6 galaxies?
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11150
Title:
Beta
Pic Polarimetry with NICMOS
PI:
James
Graham
PI
Institution:
University
of California - Berkeley
Debris
disk stars host transient dust grains that comprise a collisional
cascade
with sizes ranging from planetesimals to the sub-micron. In addition
to
the gravity of the host star and any planets present, these grains are
subject
to size-dependent non-gravitational forces, e.g., corpuscular drag and
radiation
pressure. When a steep spectrum of grain sizes prevails, such as the
Dohnanyi
distribution, scattered light images preferentially trace grains with
dimensionless
size parameter of order unity. Thus images in scattered
starlight
provide unique windows on the balance of forces acting on grains at
a
specific size. Therefore, in an A star system such as beta Pic, the
near-IR
is
dominated by grains close to the blow out size and therefore NICMOS
traces
dust
on hyperbolic orbits. Scattering
is fundamentally polarization
sensitive,
and measurements that record intensity literally see only half the
picture.
If linear polarization is measured then the elements of the complex
scattering
matrix can be reconstructed. These matrix elements provide
fundamental
constraints on the size, composition and structure of the
scatterers.
Notably, polarimetry can be used to break the degeneracy between
scattering
asymmetry, g, and the radial dust gradient, which are otherwise
covariant
in an edge-on disk. Thus, we can use polarimetry to localize the
parent
bodies in the beta Pic disk. In
beta Pic, dust is thought to originate
mainly
from the sublimation of cometary bodies near periastron. The
irradiation
of cometary material leads to sublimation and photodissociation of
ices
forming porous grains consisting of a matrix of refractory material.
Such
grains
have a characteristic scattering signature in polarized light that can
be
distinguished from compact grains that arise from collisional erosion of
asteroidal
material.
======================================================================
Proposal
Category: GO
Scientific
Category: STAR FORMATION
ID:
11151
Title:
Evaluating
the Role of Photoevaporation of Protoplanetary Disk Dispersal
PI:
Gregory
Herczeg
PI
Institution:
California
Institute of Technology
Emission
produced by accretion onto the central star leads to
photoevaporation,
which may play a fundamental role in disk dispersal.
Models
of
disk photoevaporation by the central star are challenged by two
potential
problems: the emission
produced by accretion will be substantially weaker for
low-mass
stars, and photoevaporation must continue as accretion slows.
Existing
FUV spectra of CTTSs are biased to solar-mass stars with high
accretion
rates, and are therefore insufficient to address these problems. We
propose
use HST/ACS SBC PR130L to obtain FUV spectra of WTTSs and of CTTSs at
low
masses and mass accretion rates to provide crucial data to evaluate
photoevaporation
models. We will estimate the FUV
and EUV luminosities of
low-mass
CTTSs with small mass accretion rates, CTTSs with transition disks
and
slowed accretion, and of magnetically-active WTTSs.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11152
Title:
Probing
the compact dust disk of a nearby Classical T Tauri Star
PI:
Bruce
Macintosh
PI
Institution:
Lawrence
Livermore National Laboratory
BP
Psc is a high Galactic latitude (b = -57), bright, IRAS source that
generally
has been classified as a T Tauri star but little studied to date. We
have
carried out a multiwavelength ground-based study of this object and find
that
it is most likely a ~10 Myr classical T Tauri star surrounded by a gas
and
dust disk, and less than 100 pc from Earth, making it one of the oldest
and
closest such stars known. Near-IR AO images and IR photometry show it is
surrounded
by an compact (0.2"), almost-edge-on, optically
thick disk of dust
with
a wide range of temperatures. We propose a multiwavelength polarimetric
study
of the compact disk to support quantitative modeling to recover disk and
dust
parameters. We also propose coronagraphic imaging to search for larger-
scale
dust structures invisible in ground-based images, and narrowband imaging
of
an outflow jet and associated Herbig-Haro objects to study their
structure
and
determine a kinematic distance of the system. A massive compact disk
surrounding
an isolated 10 Myr star is a unique environment for planet
formation,
and its proximity to Earth allows HST to study it in detail.
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11153
Title:
The
Physical Nature and Age of Lyman Alpha Galaxies
PI:
Sangeeta
Malhotra
PI
Institution:
Arizona
State University
In
the simplest scenario, strong Lyman alpha emission from high redshift
galaxies
would indicate that stellar populations younger than 10 Myrs dominate
the
UV. This does not, however, constrain the stellar populations older than
100
Myrs, which do not contribute to UV light. Also,
the Lyman alpha line can
be
boosted if the interstellar medium is both clumpy and dusty. Different
studies
with small samples have reached different conclusions about the
presence
of dust and old stellar populations in Lyman alpha emitters. We
propose
HST-NICMOS and Spitzer-IRAC photometry of
35 Lyman-alpha galaxies at
redshift
4.5<z<6.5, in order to determine their spectral energy
distribution
(SED)
extending through rest-frame optical. This will allow us to measure
accurately
(1) The total stellar mass in these objects, including old stars
which
may have formed at redshifts (z > 8) not easily probed by any other
means. (2) The dust extinction in the
rest-frame UV, and therefore a
correction
to their present star-formation rates.
Taken together, these two
quantities
will yield the star-formation histories of Lyman alpha galaxies,
which
form fully half of the known galaxies at z=4-6. They will tell us
whether
these are young or old galaxies by straddling the 4000A break. Data
from
NICMOS is essential for these compact and faint (i=25-26th magnitude AB)
high
redshift galaxies, which are too faint for good near-IR photometry from
the
ground.
======================================================================
Proposal
Category: GO
Scientific
Category: HOT STARS
ID:
11154
Title:
Optical-UV
Spectrum of the Middle-aged Pulsar B1055-52
PI:
George
Pavlov
PI
Institution:
The
Pennsylvania State University
The
middle-aged radio, X-ray and gamma-ray pulsar B1055-52 is one of the few
pulsars
that allow a multiwavelength study of pulsar radiation. An optical
counterpart
of the pulsar has been detected with the HST FOC, but it was
observed
in only one filter (F342W, m=24.9). To understand the nature of the
pulsar
radiation, its spectrum must be measured in a broad wavelegth range. We
propose
imaging observations of the pulsar's counterpart with
WFPC2 in the
red
part of the spectrum and ACS/SBC in the UV part to measure the broadband
spectral
distribution, compare it with the X-ray spectrum, and investigate the
thermal
and magnetospheric components of the pulsar's radiation.
======================================================================
Proposal
Category: GO
Scientific
Category: STAR FORMATION
ID:
11155
Title:
Dust
Grain Evolution in Herbig Ae Stars:
NICMOS
Coronagraphic Imaging and Polarimetry
PI:
Marshall
Perrin
PI
Institution:
University
of California - Berkeley
We
propose to take advantage of the sensitive coronagraphic capabilities of
NICMOS
to obtain multiwavelength coronagraphic imaging and polarimetry of
primordial
dust disks around young intermediate-mass stars (Herbig Ae stars),
in
order to advance our understanding of how dust grains are assembled into
larger
bodies. Because the polarization
of scattered light is strongly
dependent
on scattering particle size and composition, coronagraphic imaging
polarimetry
with NICMOS provides a uniquely powerful tool for measuring grain
properties
in spatially resolved circumstellar disks. It
is widely believed
that
planets form via the gradual accretion of planetesimals in gas-rich,
dusty
circumstellar disks, but the connection between this suspected process
and
the circumstellar disks that we can now observe around other stars
remains
very
uncertain. Our proposed
observations, together with powerful 3-D
radiative
transfer codes, will enable us to quantitatively determine dust
grain
properties as a function of location within disks, and thus to test
whether
dust grains around young stars are in fact growing in size during the
putative
planet-formation epoch. HST
imaging polarimetry of Herbig Ae stars
will
complement and extend existing polarimetric studies of disks around
lower-mass
T Tauri stars and debris disks around older main-sequence stars.
When
combined with these previous studies, the proposed research will help us
establish
the influence of stellar mass on the growth of dust grains into
larger
planetesimals, and ultimately to planets.
Our results will also let us
calibrate
models of the thermal emission from these disks, a critical need for
validating
the properties of more distant disks inferred on the basis of
spectral
information alone.
======================================================================
Proposal
Category: SNAP
Scientific
Category: SOLAR SYSTEM
ID:
11156
Title:
Monitoring
Active Atmospheres on Uranus and Neptune
PI:
Kathy
Rages
PI
Institution:
SETI
Institute
We
propose Snapshot observations of Uranus and Neptune to monitor changes
in
their
atmospheres on time scales of weeks and months. Uranus
equinox is only
months
away, in December 2007. Hubble
Space Telescope observations during the
past
several years (Hammel et al. 2005, Icarus 175, 284 and references
therein)
have revealed strongly wavelength-dependent latitudinal structure,
the
presence of numerous visible-wavelength cloud features in the northern
hemisphere,
at least one very long-lived discrete cloud in the southern
hemisphere,
and in 2006 the first dark spot ever seen on Uranus.
Long-term
ground-based
observations (Lockwood and Jerzekiewicz, 2006, Icarus 180, 442;
Hammel
and Lockwood 2007, Icarus 186, 291) reveal seasonal brightness changes
whose
origins are not well understood. Recent near-IR images of Neptune
obtained
using adaptive optics on the Keck Telescope, together with HST
observations
(Sromovsky et al. 2003, Icarus 163, 256 and references therein)
which
include previous Snapshot programs (GO 8634, 10170, 10534) show a
general
increase in activity at south temperate latitudes until 2004, when
Neptune
returned to a rather Voyager-like appearance. Further
Snapshot
observations
of these two dynamic planets will elucidate the nature of long-
term
changes in their zonal atmospheric bands and clarify the processes of
formation,
evolution, and dissipation of discrete albedo features.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11157
Title:
NICMOS
Imaging Survey of Dusty Debris Around Nearby Stars Across the Stellar
Mass
Spectrum
PI:
Joseph
Rhee
PI
Institution:
University
of California - Los Angeles
Association
of planetary systems with dusty debris disks is now quite secure,
and
advances in our understanding of planet formation and evolution can be
achieved
by the identification and characterization of an ensemble of debris
disks
orbiting a range of central stars with different masses and ages.
Imaging
debris disks in starlight scattered by dust grains remains technically
challenging
so that only about a dozen systems have thus far been imaged. A
further
advance in this field needs an increased number of imaged debris
disks. However, the technical challege of such
observations, even with the
superb
combination of HST and NICMOS, requires the best targets.
Recent HST
imaging
investigations of debris disks were sample-limited not limited by the
technology
used. We performed a search for
debris disks from a IRAS/Hipparcos
cross
correlation which involved an exhaustive background contamination check
to
weed out false excess stars. Out
of ~140 identified debris disks, we
selected
22 best targets in terms of dust optical depth and disk angular size.
Our
target sample represents the best currently available target set in
terms
of
both disk brightness and resolvability.
For example, our targets have
higher
dust optical depth, in general, than newly identified Spitzer disks.
Also,
our targets cover a wider range of central star ages and masses than
previous
debris disk surveys. This will help us to investigate planetary
system
formation and evolution across the stellar mass spectrum.
The
technical
feasibility of this program in two-gyro mode guiding has been proven
with
on-orbit calibration and science observations during HST cycles 13, 14,
and
15.
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11158
Title:
HST
Imaging of UV emission in Quiescent Early-type Galaxies
PI:
R.
Rich
PI
Institution:
University
of California - Los Angeles
We
have constructed a sample of early type galaxies at z~0.1 that have blue
UV-optical
colors, yet also show no signs of optical emission, or extended
blue
light. We have cross-correlated
the SDSS catalog and the Galaxy
Evolution
Explorer Medium Imaging Survey to select a sample of galaxies where
this
UV emission is strongest. The origin of the UV rising flux in these
galaxies
continues to be debated, and the possibility that some fraction of
these
galaxies may be experiencing low levels of star formation cannot be
excluded. There is also a possibility that
low level AGN activity (as
evidenced
by a point source) is responsbile
We propose to image the UV
emission
using the HST/SBC and to explore the morphology of the UV emission
relative
to the optical light.
======================================================================
Proposal
Category: GO
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11159
Title:
The
True Galactic Bulge Luminosity Function
PI:
R.
Rich
PI
Institution:
University
of California - Los Angeles
We
propose to obtain second epoch imaging of the deep Galactic bulge field
observed
using NICMOS by Zoccali et al. (2000).
The bulge luminosity and mass
function
suffered from 30-50% contamination by foreground disk stars, which
was
impossible to correct for in the original study. Revisiting
the field
after
9 years, we propose to segregate the foregound disk stars because they
have
large transverse velocities, thus revealing the luminosity function of
Galactic
bulge low mass stars to near the hydrogen burning limit.
The slope
of
the mass function has implications for galaxy formation and for
understanding
the nature of microlensing in the Galactic bulge.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11160
Title:
Escape
fraction and stellar populations in a highly magnified Lyman-Break
Galaxy
PI:
Johan
Richard
PI
Institution:
California
Institute of Technology
Understanding
how star-forming galaxies contribute to cosmic reionization is
one
of the frontiers of observational cosmology. A key ingredient in this
issue
is measuring the escape fraction of Lyman-continuum photons in high
redshift
galaxies (z>3). Gravitationally lensed Lyman-break galaxies (LBGs)
act
as important laboratories for studying the resolved physical properties
at
sub-kpc
scales with high signal-to-noise. Correlating the local escape
fraction
with physical parameters derived from stellar population modeling
(such
as the star formation rate, age and reddening) will offer new insights
into
understanding the physical processes involved with the production of
ionizing
photons. We propose here follow-up
observations of the "Cosmic Eye",
a
remarkable, highly magnified (x 30), Lyman-break galaxy at z~3.07 using
WFPC2
and NICMOS. Deep ultraviolet WFPC2 imaging will provide a detailed study
of
variations in the escape fraction, while WFPC2 and NICMOS/NIC2 imaging
will
complement
the current broad-band detections to allow a precise modeling of
the
spatially-dependent spectral energy distribution. This will allow the
first
comprehensive analysis between the escape fraction, the local SED and
the
dynamics of a distant galaxy.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11161
Title:
Revealing
the Explosion Geometry of Nearby GRB-SNe
PI:
Alicia
Soderberg
PI
Institution:
California
Institute of Technology
The
connection between gamma-ray bursts and Type Ibc supernovae is well-
established
in broad terms. However, our
recent identification of an
intermediate
class of sub-energetic GRBs, and the overall overlap in Nickel
production
between GRB-SNe and ordinary SNe Ibc suggest that the properties
leading
to the production of a relativistic engine are yet to be uncovered. A
fundamental
difference between the two classes of explosions may be imprinted
in
the overall geometry of the explosion. The relativistic component of
GRBs
is
known to be highly collimated, but it is unclear if the SN blast is
spherical
or mildly collimated as well. Here we propose HST observations of
the
late (>30 days) decay tails of two GRB-SNe as an independent measure
of
the
Nickel mass synthesized in the explosion.
A comparison to the Nickel mass
inferred
from the peak brightness of the SNe will provide a direct measure of
the
explosion asymmetry, since at late time the explosion is essentially
spherical.
These observations will form the core of a multi-wavelength
(optical,
X-ray, radio) effort to fully characterize all aspects of the
explosions,
from the energy and geometry of the relativistic material (VLA,
Chandra)
to the early SN evolution (Keck, Magellan). The
proposed
observations
require two slow-response (>30 days) TOOs, ideally suited to the
2-gyro
operations of HST.
======================================================================
Proposal
Category: GO
Scientific
Category: HOT STARS
ID:
11162
Title:
Understanding
the Long Term Impacts of Low Magnetic Accretion
PI:
Paula
Szkody
PI
Institution:
University
of Washington
The
low accretion rate Polar EF Eri has been in a low state for more than 9
years.
Our recent GALEX photometry revealed a source of UV light that is
producing
more flux than the white dwarf and which is highly modulated on the
81
min orbital period of the system. We request UV spectra with the SBC on
the
ACS
to resolve whether limb darkening or cyclotron emission can explain the
observed
phenomena and provide insight on the long term heating effects under
low
accretion scenarios.
======================================================================
Proposal
Category: GO
Scientific
Category: HOT STARS
ID:
11163
Title:
Accreting
Pulsating White Dwarfs in Cataclysmic Variables
PI:
Paula
Szkody
PI
Institution:
University
of Washington
Recent
ground-based observations have increased the number of known pulsating
white
dwarfs in close binaries with active mass transfer (cataclysmic
variables)
from 5 to 11 systems. Our past Cycles 8 and 11 STIS observations of
the
first 2 known, followed by our Cycle 13 SBC observations of the next 3
discovered,
revealed the clear presence of the white dwarf and increased
amplitude
of the pulsations in the UV compared to the optical. The
temperatures
derived from the UV spectra show 4 systems are much hotter than
non-interacting
pulsating white dwarfs. A larger sample is needed to sort out
the
nature of the instability strip in accreting pulsators i.e. whether
effects
of composition and rotation due to accretion result in a well-defined
instability
strip as a function of Teff.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11164
Title:
Molecular
Hydrogen Disks Around T Tauri Stars
PI:
David
Weintraub
PI
Institution:
Vanderbilt
University
We
propose to measure the properties of planetary system-sized disks around
Sun-like,
pre-main sequence stars by imaging the inner parts of these disks
for
the first time in gaseous emission from their most dominant constituent,
molecular
hydrogen gas. Specifically, we will use the F212N filter and NICMOS
to
determine the spatial distribution of ro-vibrational H2 emission from
protoplanetary
disks around selected classical and weak-lined T Tauri stars.
The
target stars are among those detected by members of this team through
high
resolution,
ground-based infrared spectroscopy. The spectra reveal H2 emission
at
the rest velocities of the stars and at positions spatially coincident
with
the
stars at the spatial resolution of the spectroscopic data. This imaging
experiment,
which is impossible to do using ground-based facilities, is
possible
using the NICMOS camera aboard the HST because the point spread
function
of this system is extremely stable and can be measured to a very high
accuracy.
This experiment is an important test of the interpretation that the
2.122
micron H2 line emission seen toward T Tauri stars is produced at
distances
of 10 to 30 AU from the stars, the region in which giant planets are
expected
to form around these stars. These observations will contribute toward
developing
a better understanding of the process, likelihood, and timescale
for
the formation of planets around Sun-like stars.
======================================================================
Proposal
Category: GO
Scientific
Category: STAR FORMATION
ID:
11165
Title:
The
Radius of the "Super-Neptune" HD 149026b
PI:
Joshua
Winn
PI
Institution:
Massachusetts
Institute of Technology
Current
measurements suggest that the transiting exoplanet HD 149026b is a
"super-Neptune,"
with an enormous heavy-element core. The existence of such a
planet
is a major challenge to planet formation theories. We propose to place
the
radius measurement on much firmer footing, by obtaining a NICMOS light
curve
with 0.4 mmag precision and 13 sec cadence. We will improve the radius
measurement
by a factor of 2.3, and more importantly, the result will be more
robust
because we will determine the stellar radius directly from the data.
Numerous
attempts to do this from the ground have failed.
======================================================================
Proposal
Category: GO
Scientific
Category: AGN/QUASARS
ID:
11166
Title:
The
Mass-dependent Evolution of the Black Hole-Bulge Relations
PI:
Jong-Hak
Woo
PI
Institution:
University
of California - Santa Barbara
In
the local universe, the masses of giant black holes
are correlated with
the
luminosities, masses and velocity dispersions of their host galaxy
bulges.
This
indicates a surprisingly close connection between the evolution of
galactic
nuclei (on parsec scales) and of stars on kpc scales. A key
observational
test of proposed explanations for these correlations is to
measure
how they have evolved over cosmic time. Our ACS imaging of 20 Seyfert
1
galaxies at z=0.37 showed them to have smaller bulges (by a factor of
3) for
a
given central black hole mass than is found in galaxies in the
present-day
universe.
However, since all our sample galaxies had black hole masses in the
range
10^8.0--8.5 Msun, we could only measure the OFFSET in black hole mass to
bulge
luminosity ratios from the present epoch. By extending this study to
black
hole masses another factor of 10 lower, we propose to determine the full
CORRELATION
of black hole mass with host galaxy properties at a lookback time
of
4 Gyrs and to test mass-dependency of the evolution. We have selected 14
Seyfert
galaxies from SDSS DR5 whose narrow Hbeta emission lines (and
estimated
nuclear luminosities) imply that they have black hole masses around
10^7
Msuns. We will soon complete our Keck spectroscopic measures of their
bulge
velocity dispersions. We need a
1-orbit NICMOS image of each galaxy to
separate
its nonstellar luminosity from its bulge and disk. This will allow us
to
make the first determination of the full black hole/bulge relations at
z=0.37
(e.g. M-L and M-sigma), as well as a test of whether active galaxies
obey
the Fundamental Plane relation at that epoch.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11167
Title:
A
Unique High Resolution Window to Two Strongly Lensed Lyman Break
Galaxies
PI:
Sahar
Allam
PI
Institution:
Fermi
National Accelerator Laboratory (FNAL)
On
rare occasions, the otherwise very
faint Lyman Break Galaxies (LBGs) are
magnified by gravitational lensing to provide
exceptional targets for
detailed
spectroscopic and imaging studies. We propose HST WFPC2 and NICMOS
imaging
of two strongly lensed Lyman Break Galaxies (LBGs)
that were recently
discovered by members of our
team. These
two LBGs -- the "8 O'Clock Arc"
and
the "SDSS J1206+5142
Arc" -- are currently the
brightest known LBGs,
roughly
3 times brighter than the
former record-holder, MS1512-cB58
(a.k.a.
"cB58").
The z=2.73 "8 O'Clock Arc" extends ~10 arcsec in length and is
magnified
by a factor of 12. The z=2.00
"SDSS J1206+5142 Arc" also extends
~10
arcsec in length and is magnified by a factor of 30.
Due to their
brightness
and magnification, these two strongly lensed LBGs offer an
unprecedented
opportunity for the very detailed investigation of two
individual
galaxies at high redshift.
We are currently pursuing a vigorous
ground-based
campaign to obtain multi-wavelength (UV,
optical, NIR, radio)
observations
of these two
LBGs, but our
campaign currently lacks a
means
of
obtaining high-resolution
optical/NIR imaging -- a lack that
currently
only
HST can address. Our prime objective for this proposal is to obtain high
resolution
HST images of these two systems with
two-orbit WFPC2 images in the
BVI
bands and two-orbit NICMOS/NIC2 images in the J
and H bands. These data
will
allow us to construct detailed lensing models, probe the mass and light
profiles
of the lenses and their environments, and constrain the star
formation
histories and rest-frame UV/optical spectral energy distributions of
the
LBGs.
======================================================================
Proposal
Category: GO
Scientific
Category: STAR FORMATION
ID:
11168
Title:
The
IMF in the Hidden Galactic Starburst W49A
PI:
Bernhard
Brandl
PI
Institution:
Universiteit
Leiden
W49A
is one of the most luminous and prolific massive star formation regions
in
the disk of our Milky Way. Given the presence of several very massive OB
clusters
as well as an unusually high concentration of many young ultra-
compact
HII regions (UCHIIR) -- all embedded in about 1 million solar masses
of
molecular gas -- it is arguably the best Galactic template for a
luminous
starburst
region. We propose to obtain
NICMOS imaging of the central part of
W49A,
covering a strip from the central, massive OB cluster to the ring of
UCHIIRs.
Our goals are to resolve and characterize the central star cluster
and
determine its IMF down to about 1 solar mass. We want to characterize
the
distribution
of intermediate-mass YSOs, and identify the NIR counterparts to
the
UCHIIRs. The combination of the proposed HST/NICMOS data with our
recently
obtained
Spitzer observations would allow a great step forward in the
understanding
of massive star and cluster formation.
======================================================================
Proposal
Category: GO
Scientific
Category: SOLAR SYSTEM
ID:
11169
Title:
Collisions
in the Kuiper belt
PI:
Michael
Brown
PI
Institution:
California
Institute of Technology
For
most of the 15 year history of observations of Kuiper belt objects, it
has
been
speculated that impacts must have played a major role in shaping the
physical
and chemical characteristics of these objects, yet little direct
evidence
of the effects of such impacts has been seen. The past 18 months,
however,
have seen an explosion of major new discoveries giving some of the
first
insights into the influence of this critical process. From a diversity
of
observations we have been led to the hypotheses that:
(1) satellite-forming
impacts
must have been common in the Kuiper belt; (2) such impacts led to
significant
chemical modification; and (3) the outcomes of these impacts are
sufficiently
predictable that we can now find and study these impact-derived
systems
by the chemical and physical attributes of both the satellites and the
primaries.
If our picture is correct, we now have in hand for the first time a
set
of incredibly powerful tools to study the frequency and outcome of
collisions
in the outer solar system. Here we propose three linked projects
that
would answer questions critical to the multiple prongs of our
hypothesis.
In
these projects we will study the chemical effects of collisions through
spectrophotometric
observations of collisionally formed satellites and through
the
search for additional satellites around primaries with potential impact
signatures,
and we will study the physical effects of impacts through the
examination
of tidal evolution in proposed impact systems. The
intensive HST
program
that we propose here will allow us to fully test our new hypotheses
and
will provide the ability to obtain the first extensive insights into
outer
solar
system impact processes.
======================================================================
Proposal
Category: GO
Scientific
Category: SOLAR SYSTEM
ID:
11170
Title:
UV
Imaging of the Martian Corona and the Escape of Hydrogen
PI:
John
Clarke
PI
Institution:
Boston
University
ACS
SBC UV imaging observations of Mars are proposed to study the extended
hydrogen
corona, with application to the escape of hydrogen and the history of
water
on Mars. These observations will
be scheduled when Mars is distant from
the
Earth, so that a field of view of +/- 4-5 Mars radii can be obtained to
image
the full range of the highly extended martian hydrogen corona through
its
H Ly alpha emission. The
observations will also be obtained when the Sun-
Earth-Mars
angle is close to 90 degrees, so that any asymmetry along the Mars-
Sun
line can be observed. The observed
2-dimensional brightness distribution
will
be related to local density using two existing radiative transfer codes,
and
the upward flux and velocity distributions will be determined by
comparison
with runs from an exospheric distribution model. These
observations,
combined with simultaneous Ly alpha observations by the SPICAM
instrument
on Mars Express from within the atmosphere, will provide the first
tight
constraints on the total escape flux and importance of nonthermal
processes
on the rate of escape.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM IN EXTERNAL GALAXIES
ID:
11171
Title:
Confirming
Light Echoes from SN 2006X in M100
PI:
Arlin
Crotts
PI
Institution:
Columbia
University in the City of New York
We
propose a minimal investment of spacecraft time to discover and confirm
a
light
echo from Supernova 2006X in M100, the closest Type Ia in many years.
Our
spectroscopic and photometric data indicate that this SN sits behind a
large
amount of interstellar dust likely to produce a strong echo signal.
This
is one of very few cases where we will be able to study the three-
dimensional
environment of a SN Ia in full detail, and begin to understand how
environmental
effects play into the evolutionary and observational factors
which
influence the utility of SN Ia as standard candles for probing
cosmology. We propose an efficient program to
definitively detect (or not) a
light
echo of reasonable signal strength, to confirm that it is an echo by
demonstrating
apparent superluminal motion if it exists, to map the three-
dimensional
geometry of the reflecting interstellar structures, and to detail
the
reflectance properties of the dust which can be used to constrain its
grain
size and composition distribution.
======================================================================
Proposal
Category: GO
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11172
Title:
Defining
Classes of Long Period Variable Stars in M31
PI:
Arlin
Crotts
PI
Institution:
Columbia
University in the City of New York
We
propose a thrifty but information-packed investigation (1440 exposures
total)
with NICMOS F205W, F160W and F110W providing crucial information about
Long
Period Variables in M31, at a level of detail that has recently allowed
the
discovery of new variable star classes in the Magellanic Clouds, a very
different
stellar population. These
observations are buttressed by an
extensive
map of the same fields with ACS and WFPC2 exposures in F555W and
F814W,
and a massive ground-based imaging patrol producing well-sampled light
curves
for more than 400,000 variable stars.
Our primary goal is to collect
sufficient
NIR data in order to analyze and classify the huge number of long-
period
variables in our catalog (see below) through Period-Luminosity (P/L)
diagrams. We will produce accurate P/L diagrams
for both the bulge and a
progression
of locations throughout the disk of M31.
These diagrams will be
similar
in quality to those currently in the Magellanic Clouds, with their
lower
metallicity, radically different star formation history, and larger
spread
in distance to the variables. M31
offers an excellent chance to study
more
typical disk populations, in a manner which might be extended to more
distant
galaxies where such variables are still visible, probing a much more
evenly
spread progenitor age distribution than cepheids (and perhaps useful as
a
distance scale alternative or cross-check). Our
data will also provide a
massive
and unique color-magnitude dataset, and
allow us to confirm the
microlensing
nature of a large sample of candidate lensed sources in M31. We
expect
that this study will produce several important results, among them a
better
understanding of P/L and P/L-color relations for pulsating variables
which
are essential to the extragalactic distance ladder, will view these
variables
at a common distance over a range of metallicities (eliminating the
distance-error
vs. metallicity ambiguity between the LMC and SMC), allow
further
insight into possible faint-variable mass-loss for higher
metallicities,
and in general produce a sample more typical of giant disk
galaxies
predominant in many studies.
======================================================================
Proposal
Category: GO
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11173
Title:
Completing
an Accurate Map of M31 Microlensing
PI:
Arlin
Crotts
PI
Institution:
Columbia
University in the City of New York
The
halo microlensing masses detected in the MACHO survey (claimed to
compose
about
20% of the Galaxy's mass) represent a major enigma in astrophysics, one
that
must be effectively cross-examined by an independent test.
We have
completed
a large, densely-sampled survey of M31 that can reveal in another
galaxy
such a halo microlensing signal if it exists. In
a previous
HST/ACS+WFPC2
program (GO 10273, Cycle 13, 16 orbits) we were able to learn
considerably
more about a subsample of these M31 microlensing events.
We were
pleased
to find that in most cases we could isolate the source star for each
event,
find its baseline flux and colors (essential for ruling out classes of
confusing
variable stars), test for misidentification of background
supernovae,
and measure the Einstein parameters, which constrain the range of
most
likely lens mass. (These Cycle 13
results are published in The
Astrophysical
Journal Letters.) We propose to
finish the job, taking a
similar
series of exposures to more than double the sample of well-constrained
microlensing
events, which together with the larger ground-based sample for
which
we are completing our analyses will provide 20-30 M31 bona fide
microlensing
events observed by HST. This will
be done via a series of
targetted
PC exposures, meant to maximize the number of candidates studied,
one
(or two) at a time. A sample of
this size and quality should be
sufficient
to settle the issue of a significant contribution to the halos of
galaxies
by stellar-mass lenses.
Furthermore, if there is a surplus of such
microlensing
events above what might be expected from stars alone, the higher
quality
of information will allow us to more accurately describe the spatial
distribution
of these lenses. We will also
complete several unique studies of
M31
stellar populations, both in support of the microlensing measurement and
in
their own right.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11174
Title:
A
Spitzer/X-ray candidate cluster at z>2:
NICMOS
imaging
PI:
Emanuele
Daddi
PI
Institution:
Commissariat
a l'Energie Atomique (CEA)
We
propose deep H-band imaging with NICMOS of a remarkable z>2 cluster
of
galaxy
candidate. Over a 1000 arcmin^2 field imaged with Spitzer's IRAC and
MIPS
we have discovered a compact (<30'' diameter) concentration of
extremely
red
galaxies with a factor of >40 overdensity over the adjacent field.
Among
these
galaxies for which we can derive meaningful photometric redshifts, 17
are
consistent with zphot=2-2.5, making very likely that the concentrationis
is
a real cluster at such high redshift. This is further supported by a 3.5
sigma
detection of extended X-Ray emission on Newton-XMM data, by a likely
color-magnitude
sequence of red galaxies, and by the presence of a giant
galaxy
consistent with a BCG at the cluster redshift. While spectroscopic
confirmation
of the cluster might result prohibitive with current facilities,
HST
high resolution imaging will allow us to gain crucial information for
the
study
and scientific exploitation of this hot gas hosting, record high-z
cluster
of galaxies. The HST high resolution observations will allow us to
unveil
the rest frame optical morphologies of
the galaxies and confirm the
presence
of ellipticals in the structure, detect and characterize the color-
magnitude
relation, measure their effective radii and construct their Kormendy
relation
for the passively evolving subsample, improve the photometric
redshift
estimates to confirm the real cluster nature of the structure,
estimate
stellar masses and check for possible deviations from the local mass-
size
relation, search for mergers and AGNs, and establish a cluster benchmark
for
cluster-field comparisons at this highest redshift.
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11175
Title:
UV
Imaging to Determine the Location of Residual Star Formation in
Galaxies
Recently Arrived on the Red Sequence
PI:
Sandra
Faber
PI
Institution:
University
of California - Santa Cruz
We
have indentified a sample of low-redshift (z = 0.04 - 0.10) galaxies
that
are
candidates for recent arrival on the red sequence.
They have red optical
colors
indicative of old stellar populations, but blue UV-optical colors that
could
indicate the presence of a small quantity of continuing or very recent
star
formation. However, their spectra
lack the emission lines that
characterize
star-forming galaxies. We propose
to use ACS/SBC to obtain high-
resolution
imaging of the UV flux in these galaxies, in order to determine the
spatial
distribution of the last episode of star formation.
WFPC2 imaging
will
provide B, V, and I photometry to measure the main stellar light
distribution
of the galaxy for comparison with the UV imaging, as well as to
measure
color gradients and the distribution of interstellar dust.
This
detailed
morphological information will allow us to investigate the hypothesis
that
these galaxies have recently stopped forming stars and to compare the
observed
distribution of the last star formation with predictions for several
different
mechanisms that may quench star formation in galaxies.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11176
Title:
Location
and the Origin of Short Gamma-Ray Bursts
PI:
Andrew
Fruchter
PI
Institution:
Space
Telescope Science Institute
During
the past decade extraordinary progress has been made in determining the
origin
of long-duration gamma-ray bursts.
It has been conclusively shown
that
these objects derive from the deaths of massive stars.
Nonetheless, the
origin
of their observational cousins, short-duration gamma-ray bursts (SGRBs)
remains
a mystery. While SGRBs are
widely thought to result from the
inspiral
of compact binaries, this is a conjecture. A
number of hosts of
SGRBs
have been identified, and have been used by some to argue that SGRBs
derive
primarily from an ancient population (~ 5 Gyr); however, it is not
known
whether this conclusion more accurately reflects selection biases or
astrophysics. Here we propose to employ a variant of
a technique that we
pioneered
and used to great effect in elucidating the origins of long-duration
bursts. We will examine the degree to
which SGRB locations trace the red or
blue
light of their hosts, and thus old or young stellar populations. This
approach
will allow us to study the demographics of the SGRB population in a
manner
largely free of the distance dependent selection effects which have so
far
bedeviled this field, and should give direct insight into the age of the
SGRB
progenitor population.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11177
Title:
The
Nature of z=3 Lyman-Alpha Emitters
PI:
Caryl
Gronwall
PI
Institution:
The
Pennsylvania State University
The
advent of large mosaic CCD cameras on 4 -- 8 m class telescopes has
recently
led to a revolution in our ability to detect primordial galaxies.
Today,
large numbers of strong Ly-alpha
emitters (LAEs) are being discovered
between
2.4 < z < 6. These are
important objects: not
only do they sample a
part
of the galaxy luminosity function that is inaccessible to the
Lyman-break
technique,
but they also tend to be younger and less chemically evolved. In
fact,
the LAEs now being found are currently our best candidates for galaxies
in
the act of formation. To
investigate the properties of this class of
objects,
we have conducted an extremely deep narrow-band (5000 Angstrom; FWHM
=
50 Angstrom) and broad-band (UBVRIzJK) survey of the Extended Chandra
Deep
Field
South, and have identified a homogeneous sample of strong Ly-alpha
emitters
at z = 3.11. Twenty-seven of these
objects are located within the
region
surveyed by Great Observatories Origins Deep Survey (GOODS) and have
detailed
morphological information available from the rest-frame ultraviolet.
We
propose 0.2" resolution narrow-band imaging of 11 of our LAEs using the
F502N
filter of WFPC2. By comparing the
Ly-alpha and rest-frame UV continuum
morphologies
of these galaxies, we will be able to look for the presence of
outflows,
constrain their dust content, and test whether these objects are
truly
primordial galaxies.
======================================================================
Proposal
Category: GO
Scientific
Category: SOLAR SYSTEM
ID:
11178
Title:
Probing
Solar System History with Orbits, Masses, and Colors of Transneptunian
Binaries
PI:
William
Grundy
PI
Institution:
Lowell
Observatory
The
recent discovery of numerous transneptunian binaries (TNBs) opens a
window
into
dynamical conditions in the protoplanetary disk where they formed as
well
as
the history of subsequent events which sculpted the outer Solar System
and
emplaced
them onto their present day heliocentric orbits. To
date, at least
43
TNBs have been discovered, but only about a dozen have had their mutual
orbits
and separate colors determined, frustrating their use to investigate
numerous
important scientific questions.
The current shortage of data
especially
cripples scientific investigations requiring statistical
comparisons
among the ensemble characteristics.
We propose to obtain
sufficient
astrometry and photometry of 23 TNBs to compute their mutual orbits
and
system masses and to determine separate primary and secondary colors,
roughly
tripling the sample for which this information is known, as well as
extending
it to include systems of two near-equal size bodies.
To make the
most
efficient possible use of HST, we will use a Monte Carlo technique to
optimally
schedule our observations.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11179
Title:
Dynamics
of Clumpy Supersonic Flows in Stellar Jets and in the Laboratory
PI:
Patrick
Hartigan
PI
Institution:
Rice
University
We
propose to reobserve three stellar jets in order to quantify how rapidly
clumps
in these flows accelerate and decelerate, and to compare the results
with
ongoing numerical simulations and laboratory experiments. Each jet has
been
imaged twice before with HST, and precise proper motions have been
measured
for all emitting knots in the jets. Images from the first two epochs
show
clear differential motions between adjacent clumps, as well as shear,
and
possibly
fragmentation. The proposed third epoch will enable us to measure the
first
ever accelerations in jets, quantify errors in existing proper motion
measurements,
and observe in real time how fluid instabilities develop in
supersonic
flows. The new images will make it possible to compare the behavior
of
astrophysical flows directly with numerical simulations and with
laboratory
experiments
of bow shocks and clumpy flows in progress at the Omega laser
facility.
======================================================================
Proposal
Category: GO
Scientific
Category: COOL STARS
ID:
11180
Title:
The
Morphology of the Post-Red Supergiant IRC+10420's Circumstellar Ejecta
PI:
Roberta
Humphreys
PI
Institution:
University
of Minnesota - Twin Cities
The
extremely luminous post-red supergiant and powerful OH/IR source IRC
+10420
is surrounded by a complex circumstellar nebula. Numerous small
condensations,
arcs, jet-like rays of knots, and intriguing semi-circular
structures
are easily visible in our previous WFPC2 images. We have suggested
that
these spatially recognizable features may be evidence for episodic mass
loss
events possibly from localized active regions. We now propose to obtain
second
epoch WFPC2 images with the Planetary Camera to measure the transverse
motions
of these ejecta. Spatially resolved spectra from STIS showed that the
embedded
arcs are kinematically distinct from the spherically expanding
diffuse
nebulosity. The transverse motions in combination with radial
velocities
from the STIS spectra, will let us determine the morphology of IRC
+10420's
nebula and the structures embedded in it, its mass loss history, and
provide
clues to the mass loss mechanism responsible for the discrete
ejections.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11181
Title:
SAINTS
- Supernova 1987A INTensive Survey
PI:
Robert
Kirshner
PI
Institution:
Harvard
University
SAINTS
is a program to observe SN 1987A, the brightest supernova in 383 years,
as
it matures into the youngest supernova remnant at age 20.
HST is the
essential
tool for spatially-resolved observations of SN1987A's many
components. A violent encounter is now underway
between the fastest-moving
debris
and the circumstellar ring: the shock
excites "hotspots." The
optical,
infrared
and X-ray fluxes are rising rapidly on 6-month time scales:
we
have
organized
HST, SPITZER, and CHANDRA observations to understand these regions.
In
Cycle 16, the separate hotspots may begin to fuse as the shock fully
enters
the
circumstellar ring. Photons from
these shocks will excite previously
invisible
gas outside the ring, revealing the true extent of the mass loss
that
preceded the explosion of Sanduleak -69 202. The inner debris of the
explosion,
excited by radioactive isotopes from the explosion, is now resolved
and
seen to be aspherical, providing direct evidence on the asymmetry of the
explosion. Questions about SN 1987A remain
unanswered. How did the enigmatic
three
rings form? Precisely what
happened during the core collapse and
bounce? Is a black hole or a neutron star left
behind? The rich and deep
data
set from SAINTS will help answer these central questions of supernova
science.
======================================================================
Proposal
Category: GO
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11182
Title:
The
Mass of the Milky Way:
Orbits
for Leo I and Leo II: Second Epoch Imaging of Leo II
PI:
Konrad
Kuijken
PI
Institution:
Universiteit
Leiden
Constraining
the mass of the Galaxy at large radii remains a difficult
problem. Available data are still rather scarce,
and orbits of even a few
objects
at large radii can have a large impact.
We propose to obtain proper
motions
for the two satellites Leo I and Leo II, which orbit the Galaxy at
about
200 kpc. Together with the radial
velcoities of these glaaxies, which
are
well known, the proper motions allow space velocities ot be consructed:
these
can remove signifiicant uncertainty in the Galactic mass models, and in
particular
settle the vexed question of whether or not Leo I is
gravitationally
bound to the Galaxy. The proper
motion of Leo I is addressed
in
a companion archival proposal; here we address the WFPC2 imagery of Leo
II.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM IN EXTERNAL GALAXIES
ID:
11183
Title:
Ultraviolet
Imaging of Lyman-Alpha-Selected Galaxies at High Redshift
PI:
Crystal
Martin
PI
Institution:
University
of California - Santa Barbara
We
propose to carry out deep NICMOS/NIC2 imaging in the rest-frame,
ultraviolet
continuum of galaxies discovered in the Magellan Multi-Slit Lyman
Alpha
Survey. This spectroscopic survey
identified
ultra-faint, redshift 5.7
Lyman-alpha
emitters (LAEs) in a 15 nm wide, OH-free band at 819 nm.
Imaging
with
HST is the only way to measure their continuum intensity near rest-frame
160
nm. The ultraviolet photometry
will directly measure the rate of star
formation
in common objects; and, when combined with groundbased Lyman-alpha
luminosities,
provide a reliable cross-calibration of Lyman-alpha attenuation
and
emission equivalent width. Direct
measurement of the size of the star-
forming
regions, unresolved in the groundbased data, will extend measurements
of
the intensity of star formation to common objects in the high-redshift
universe. Gaseous outflows from these galaxies
are thought to be the source
of
their asymmetric line profiles, and area-averaged star formation rates
are
needed
to calibrate feedback recipes, as well as eventually extend the
Schmidt-Kennicutt
law to high-redshift. The three
targets proposed in
Cycle~16
lie in fields covered by major galaxy surveys, are not as bright as
the
unusually luminous sources identified by such surveys at high-redshift,
and
present an opportunity to study properties of more common galaxies at
high-redshift.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11184
Title:
Imaging
the Shock Precursor in Tycho's SNR
PI:
John
Raymond
PI
Institution:
Smithsonian
Institution Astrophysical Observatory
Cosmic
ray acceleration in supernova remant shocks requires shock precursors
where
particles are trapped by plasma turbulence. The
precursors also heat
and
compress the upstream gas, producing H alpha emission and affecting line
profiles. We propose to image the brightest
non-radiative shock in Tycho's
SNR
to measure the brightness and width of the precursor.
These measurements
will
constrain 2 key parameters in cosmic ray acceleration models, and they
will
improve the accuracy of shock speed and electron-ion equilibration
derived
from H alpha profiles.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11185
Title:
Search
for H-poor/He-rich Inclusions and a Solution to the Abundance,
Temperature
Problems
PI:
Robert
Rubin
PI
Institution:
NASA
Ames Research Center
Our
recent abundance survey of a large sample of Galactic planetary nebulae
(PNe)
has led to the discovery of a group
of super-metal-rich nebulae whose
spectra
are characterized by prominent optical recombination lines (ORLs) from
C,
N, O, & Ne ions and a large Balmer discontinuity jump. The heavy
element
abundances
derived from ORLs for several PNe are more than an order of
magnitude
higher than those derived from the traditional method based on
collisionally
excited lines (CELs), while the Balmer jump yields electron
temperatures
(Te) significantly lower than values derived from the [O III]
5007/4363
CEL line ratio. A
proposition that aspires to explain both the
nebular
abundance and Te problems is one
according to which these nebulae
contain
(at least) two distinct emission regions - one of "normal" Te (~
10000
K)
and chemical composition (~solar) and another of very low Te that is H-
deficient,
thus having high helium and metal abundances relative to hydrogen.
The
latter component emits strong He and heavy element ORLs but essentially
no
CELs.
The consistent picture that emerges from fitting a 2-component
photoionization
model to the spectroscopic data is that the H-poor component
is
in high-density inclusions, which provide only a minor fraction of the
total
nebular mass. We propose to directly detect these inclusions in the
planetary
nebula M 1-42 using WFPC2 (PC) to make a high spatial resolution
image
in the He I 5876 A ORL
and ratio it to Halpha. With NICMOS
(NIC1), we
plan
to observe the He I 10830 A line, which is substantially
collisionally
excited,
along with Palpha 18760 A. The ratio image of He I 10830 to Palpha is
expected
to be less likely to show the
inclusions, thus serving as an
important
control to the optical imaging. M 1-42 is one of the most extreme
cases
of the abundance and Te problem; it is reasonably bright and compact.
This
program has the potential to resolve a serious challenge to our current
understanding
of nebular astrophysics.
======================================================================
Proposal
Category: GO
Scientific
Category: SOLAR SYSTEM
ID:
11186
Title:
Investigation
of the spatial and temporal structure of Europa's atmospheric emissisons
PI:
Joachim
Saur
PI
Institution:
Universitat
zu Koeln
We
propose to explore the spatial structure and temporal variability of
Europa's
O2 atmosphere with ACS/SBC. Previous HST images display non-uniform
UV
emission from Europa's atmosphere, which maximizes within the disk of
Europa
on its anti-Jovian northern quadrant. These images were taken at
western
elongation and are not conclusive,
but bring up the exciting question
whether
the non-uniform emission is due to a locally enhanced
neutral
atmosphere.
A locally inhomogeneous atmosphere would imply locally modified
surface properties. This might provide clues on
inhomogeneities of the
underlying
ice structure and thus properties of a
potential subsurface ocean.
Since
the inhomogeneous emission comes from within the disk of Europa, we
propose
to study Europa at eastern and western elongation to decide if the
locally
enhanced emission is truly an
atmospheric effect. We propose to take
for
each elongation five contiguous observations within one rotation period
of
Jupiter to discriminate between a competing effect that produces
inhomogeneous
emission patterns, i.e., the
electrodynamic interaction with
Jupiter's
magnetosphere. We will use ACS/SBC with PR130L prism to
completely
separate
the two prominent FUV oxygen lines OI 1304 A and OI 1356 A emitted
from
Europa's atmosphere.
======================================================================
Proposal
Category: GO
Scientific
Category: SOLAR SYSTEM
ID:
11187
Title:
A
Deep Search for Martian Dust Rings
PI:
Mark
Showalter
PI
Institution:
SETI
Institute
It
has been long suspected that Mars is encircled by two faint rings of
dust,
one
originating from each of its moons Phobos and Deimos. Similar dust rings
are
associated with many of the small, inner moons orbiting Jupiter, Saturn,
Uranus
and Neptune. On December 31, 2007, Earth will pass through Mars'
equatorial
plane just a week after its December 24 opposition, providing an
exceedingly
rare opportunity to image the rings under nearly ideal viewing
geometry.
The next equivalent viewing opportunity occurs in 2022. Using the
Wide
Fields of WFPC2 and a highly optimized observing plan, we expect to be
able
to detect rings with edge-on reflectivities of ~ 10^-8, which is at or
below
the level where most dynamicists expect rings to be visible. This is a
factor
of 10-30 more sensitive than the detection limit we achieved during a
slightly
inferior viewing opportunity in 2001. The rings have been predicted
to
show some interesting dynamical properties, including large asymmetries
and
inclinations.
A positive detection will test these predictions, serving as an
effective
test of dynamical models developed to account for the properties of
other
faint planetary rings as well. With such a stringent limit, even a
negative
result will be of considerable interest, challenging dynamicists to
explain
the remarkably low density of dust within the Martian system.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11188
Title:
First
Resolved Imaging of Escaping Lyman Continuum
PI:
Brian
Siana
PI
Institution:
Jet
Propulsion Laboratory
The
emission from star-forming galaxies appears to be responsible for
reionization
of the universe at z>6.
However, the models that attempt to
describe
the detailed impact of high-redshift galaxies on the surrounding
inter-galactic
medium (IGM) are strongly dependent upon several uncertain
parameters. Perhaps the most uncertain is the
fraction of HI-ionizing photons
produced
by young stars which escape into the IGM.
Most attempts to measure
this
"escape fraction" (f_esc) have produced null results.
Recently, a small
subset
of z~3 Lyman Break Galaxies (LBGs) has been found exhibiting large
escape
fractions. It remains unclear
however, what differentiates them from
other
LBGs. Several models attempt to
explain how such a large fraction of
ionizing
continuum can escape through the HI and dust in the ISM (eg.
"chimneys"
created by SNe winds, globular cluster formation, etc.), each
producing
unique signatures which can be observed with resolved imaging of the
escaping
Lyman continuum. We propose a
deep, high resolution WFPC2 image of
the
ionizing continuum (F336W) and the rest-frame 1500 Angstrom continuum
(F606W)
of five of the six known LBGs with large escape fractions.
These LBGs
all
fit within a single WFPC2 pointing, yielding high observing efficiency.
Additionally,
they all have z~3.1 or higher, the optimal redshift range for
probing
the Lyman Continuum region with available WFPC2 filters.
These
factors
make our proposed sample especially suitable for follow-up. With
these
data we will discern the mechanisms responsible for producing large
escape
fractions, and therefore gain insight into the process of reionization.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11189
Title:
Probing
the early universe with GRBs
PI:
Nial
Tanvir
PI
Institution:
University
of Leicester
Cosmology
is beginning to constrain the nature of the earliest stars and
galaxies
to form in the Universe, but direct observation of galaxies at z>6
remains
highly challenging due to their scarcity, intrinsically small size,
and
high luminosity distance. GRB
afterglows, thanks to their extreme
luminosities,
offer the possibility of circumventing these normal constraints
by
providing redshifts and spectral information which couldn't be obtained
through
direct observation of the host galaxies themselves.
In addition, the
association
of GRBs with massive stars means that they are an indicator of
star
formation, and that their hosts are likely responsible for a large
proportion
of the ionizing radiation during that era. Our
collaboration is
conducting
a campaign to rapidly identify and study candidate very high
redshift
bursts, bringing to bear a network of 2, 4 and 8m telescopes with
near-IR
instrumentation. Swift has proven
capable of detecting faint, distant
GRBs,
and reporting accurate positions for many bursts in near real-time.
Here
we propose to continue our HST program of targetting GRBs at z~6 and
above. HST is crucial to this endeavour,
allowing us (a) to characterise the
basic
properties, such as luminosity and colour, and in some cases
morphologies,
of the hosts, which is essential to understanding these
primordial
galaxies and their relationship to other galaxy populations; and
(b)
to monitor the late time afterglows and hence compare them to lower-z
bursts
and test the use of GRBs as standard candles.
======================================================================
Proposal
Category: GO
Scientific
Category: SOLAR SYSTEM
ID:
11190
Title:
Probing
Uranus' Vertical Aerosol Structure at Equinox
PI:
Laurence
Trafton
PI
Institution:
University
of Texas at Austin
After
a decade of quiescence following the Voyager flybys, Uranus' atmosphere
has
been exhibiting increasing activity approaching equinox that suggests a
short
timescale, dynamical, response in addition to a long timescale,
radiative,
response to the seasonal change of hemispheric heating.
We propose
to
investigate this dichotomy by measuring Uranus' vertical aerosol
structure
over
the entire surface, including both poles, at equinox when the forcing
insolation
is hemispherically symmetric, requiring that the sub-Earth latitude
be
less than a degree. Only at equinox (every 42 years) can the entire
surface
of
the planet be viewed (over a full rotation) and mapped with the same
viewing
geometry. We will probe the morphology of the vertical haze structure
using
NICMOS narrow band filters beyond 1 micron to isolate different altitude
regimes
between the stratosphere and cloud deck and investigate its change
since
Cycle 7. We will use two complementary approaches: First,
imaging will
be
done using medium- and narrow-band filters first to locate the
dynamically-
produced
discrete cloud features, then to probe their vertical structure and
morphology.
The methane absorption bands are stronger in the proposed near-IR
(1
to 2.5 microns) than at shorter wavelengths, and the strong H2 pressure-
induced
absorption from 2.1-2.4 microns contributes to the peak opacity. This
enhances
the visibility of transient,
spatially isolated features and allows
their
structure to be probed to higher altitudes; namely, to the upper
troposphere
where they would be evidence of convective overshoot, a dynamical
manifestation
that would support strong seasonally-induced static instability.
In
addition to probing the structure with filter photometry, we will
measure
longitudinal
limb profiles to probe the vertical background haze distribution
vs
latitude. HST/NICMOS is required because it avoids telluric water
absorption
and OH+O2 emission, and has a stable, well-characterized PSF,
essential
for limb studies and extracting the vertical structure of fine
features
crossing the disk. The proposed observations would complement the
ground-based
Uranus equinox campaign.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11191
Title:
NICMOS
Imaging of a z>4 High-Redshift Ultraluminous Submillimeter Source
PI:
Wei-Hao
Wang
PI
Institution:
Associated
Universities, Inc.
We
propose 16 orbits of deep NICMOS 1.6 um imaging of GOODS850-5, a unique
z>4
candidate
SCUBA source that is bright in the submillimeter (submm) but
extremely
faint at all other wavelengths.
GOODS850-5 is a 11 mJy 850 um
source
discovered in our GOODS-N SCUBA survey.
It does not have a radio
counterpart
and its accurate location was recently determined with the SMA
interferometer. It is not detected by the GOODS-N HST
ACS imaging and is just
above
the detection limit of the ultradeep Spitzer imaging at 3.6-24 um. Its
faint
radio flux and its Spitzer color suggest a redshift of z>4, and
potentially
even z>6. It has an incredible
star formation rate of ~1000 solar
mass
per year, and it can quickly grow into a >10^11 solar mass massive
galaxy. Radio faint submm sources like
GOODS850-5 may be a new population of
high-redshift
massive galaxies that are not picked up by any of the previous
optical,
near-IR, and radio surveys, and therefore it is crucial to obtain the
redshift
of GOODS850-5. However, because of
its extreme optical faintness,
the
only way to constrain its redshift is photometric redshift with the
existing
Spitzer photometry and the proposed NICMOS 1.6 um photometry. NICMOS
is
the only instrument that can provide information about its redshift and
morphology
among all space-based and ground-based instruments at all
wavelengths. The proposed observation will provide
unique insight on galaxy
evolution
and mass assembly at high redshift.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11192
Title:
NICMOS
Confirmation of Candidates of the Most Luminous Galaxies at z > 7
PI:
Hao-Jing
Yan
PI
Institution:
Observatories
of the Carnegie Institution of Washington
While
the deepest pencil-beam near-IR survey suggested that the Universe was
too
young to build up many luminous galaxies by z ~ 7--8 (Bouwens &
Illingworth
2006), there is also evidenc indicating the contrary. It is now
known
that some galaxies with stellar masses of M>1e10 Msun were already in
place
by z ~ 6--7, which strongly suggests that their progenitors should be
significantly
more luminous, and hence detectable in deep, wide-field near-IR
surveys
(Yan et al. 2006). As galaxies at such a high redshift should manifest
themselves
as "dropouts" from the optical,
we have carried out a very wide-
field,
deep near-IR survey in the GOODS fields to search for z-band dropouts
as
candidates of galaxies at z > 7. In total, six promising candidates
have
been
found in ~ 300 sq. arcmin to J_AB ~ 24.5 mag (corresponding to restframe
M(UV)
< -22.5 mag at z ~ 7). By
constrast, the galaxy luminosity function
(LF)
suggested in BI06 would predict at most 3--5 galaxies over the entire 2-
pi
sky at this brightness level. Here
we propose to observe these candidates
with
NIC3 in F110W and F160W to further investigate their nature. If any of
these
candidates are indeed at z > 7,
the result will lead to a completely
new
picture of star formation in the early universe. If none of our
candidates
are
consistent with being at z > 7, then the depth and area of our
near-IR
survey
(from which the candidates are drawn) will let us set a very stringent
upper
limit on the bright end of the galaxy LF at those redshift. As a
result,
our program will still be able to provide new clues about the
processes
of early galaxy formation, such as their dust contents and their
merging
time scale (Yan et al. 2006).
======================================================================
Proposal
Category: GO
Scientific
Category: STAR FORMATION
ID:
11193
Title:
A
comprehensive study of the low-mass stellar population in the Galactic
starburst region NGC 3603
PI:
Wolfgang
Brandner
PI
Institution:
University
of California - Los Angeles
NGC
3603, located in the Carina spiral arm, is one of the most luminous
giant
HII
regions in the Milky Way, and as such it is often referred to as a prime
template
for extragalactic starbursts. While previous studies were focussing
on
the high and intermediate mass stellar content of the central starburst
cluster,
which powers the HII region, the effects of the starburst environment
with
its large number of ionizing O stars on the emerging low-mass population
are
unknown. As the most nearby, most easily accessible starburst, NGC 3603
provides
the best testbed to study the long-lived, low-mass stars originating
from
a starburst environment. Taking advantage of the large field of view and
high
sensitivity of WFPC2, we want to survey the stellar population in an
area
of
10pc x 10pc (6' x 6') down to a mass limit of 0.2 to 0.5 Mo. This will
enable
us to derive the total cluster mass, look for spatial variations in the
initial
mass function, determine the age of the dispersed low-mass population
in
the HII region and search for evidence of sequential star formation.
Ultimately,
we aim at reconstructing the low-mass stellar initial mass
function
of the starburst epoch in NGC 3603, which in turn will advance our
understanding
of extragalactic starburst phenomena and the emerging low-mass
stars
as observed in ancient populations. The observations of NGC 3603 are
part
of our larger effort to study intense star-forming regions in the Milky
Way,
LMC and SMC.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11194
Title:
Beyond
the Bullet: Direct Detection
of Dark Matter in Merging Galaxy Clusters
PI:
Douglas
Clowe
PI
Institution:
Ohio
University
Our
comparison of the distribution of baryons (stars and gas) and mass (from
weak
lensing) in the "Bullet" Cluster has recently yielded concrete
evidence
for
dark matter independent of basic assumptions regarding the nature of the
gravitational
force. The one incomplete aspect of the argument relates to
potential,
although highly unlikely, coincidences (special alignments along
the
line of sight, and/or fortuitious canceling in non-standard
gravitational
models)
that can always be invoked against results derived from the study of
one
object. Therefore, we proprose to
complete this line of investitgation by
increasing
the size of our sample with obsevations of two additional clusters.
Here
we propose to obtain HST WFPC2 imaging mosaics around the cores of both
clusters
to detect at high significance if the weak gravitational lensing mass
peaks
are routinely displaced from the X-ray plasma clouds and aligned with
the
galaxy concentrations in interacting clusters. With
a relatively modest
allocation
of time, we seek to complete a significant step toward the eventual
resolution
of the dark matter question.
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11195
Title:
Morphologies
of the Most Extreme High-Redshift Mid-IR- luminous Galaxies II: The `Bump' Sources
PI:
Arjun
Dey
PI
Institution:
National
Optical Astronomy Observatories, AURA
The
formative phase of some of the most massive galaxies may be extremely
luminous,
characterized by intense star- and AGN-formation. Till
now, few
such
galaxies have been unambiguously identified at high redshift, and thus
far
we have been restricted to studying the low-redshift ultraluminous
infrared
galaxies as possible analogs. We have recently discovered a sample of
objects
which may indeed represent this early phase in galaxy formation, and
are
undertaking an extensive multiwavelength study of this population. These
objects
are optically extremely faint (R>26) but nevertheless bright at mid-
infrared
wavelengths (F[24um] > 0.5 mJy). Mid-infrared spectroscopy with
Spitzer/IRS
reveals that they have redshifts z~2, implying luminosities ~1E13
Lsun. Their mid-IR SEDs fall into two broad,
perhaps overlapping, categories.
Sources
with brighter F[24um] exhibit power-law SEDs and SiO absorption
features
in their mid-IR spectra characteristic of AGN, whereas those with
fainter
F[24um] show a "bump" characteristic of the redshifted 1.6um peak
from
a
stellar population, and PAH emission characteristic of starformation. We
have
begun obtaining HST images of the brighter sources in Cycle 15 to obtain
identifications
and determine kpc-scale morphologies for these galaxies. Here,
we
aim to target the second class (the "bump" sources) with the goal of
determining
if these constitute morphologically different objects, or simply a
"low-AGN"
state of the brighter class. The
proposed observations will help us
determine
whether these objects are merging systems, massive obscured
starbursts
(with obscuration on kpc scales
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11196
Title:
An
Ultraviolet Survey of Luminous Infrared Galaxies in the Local Universe
PI:
Aaron
Evans
PI
Institution:
State
University of New York at Stony Brook
At
luminosities above 10^11.4 L_sun, the space density of far-infrared
selected
galaxies exceeds that of optically selected galaxies. These Luminous
Infrared
Galaxies (LIRGs) are primarily interacting or merging disk galaxies
undergoing
starbursts and creating/fueling central AGN. We propose far
(ACS/SBC/F140LP)
and near (WFPC2/PC/F218W) UV
imaging of a sample of 27
galaxies
drawn from the complete IRAS Revised Bright Galaxy Sample (RBGS)
LIRGs
sample and known, from our Cycle 14 B and I-band ACS imaging
observations,
to have significant numbers
of bright (23 < B < 21 mag)
star
clusters
in the central 30 arcsec. The HST
UV data will be combined with
previously
obtained HST, Spitzer, and GALEX images to (i) calculate the ages
of
the clusters as function of merger stage, (ii) measure the amount of UV
light
in massive star clusters relative to diffuse regions of star formation,
(iii)
assess the feasibility of using the UV slope to predict the far-IR
luminosity
(and thus the star formation rate) both among and within IR-
luminous
galaxies, and (iv) provide a much needed catalog of rest-frame UV
morphologies
for comparison with rest-frame UV images of high-z LIRGs and
Lyman
Break Galaxies. These observations will achieve the resolution required
to
perform both detailed photometry of compact structures and spatial
correlations
between UV and redder wavelengths for a physical interpretation
our
IRX-Beta results. The HST UV data, combined with the HST ACS, Spitzer,
Chandra,
and GALEX observations of this sample, will result in the most
comprehensive
study of luminous starburst galaxies to date.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11197
Title:
Sweeping
Away the Dust: Reliable Dark Energy
with an Infrared Hubble Diagram
PI:
Peter
Garnavich
PI
Institution:
University
of Notre Dame
We
propose building a high-z Hubble Diagram using type Ia supernovae
observed
in
the infrared rest-frame J-band. The infrared has a number of exceptional
properties. The effect of dust extinction is
minimal, reducing a major
systematic
that may be biasing dark energy measurements. Also,
recent work
indicates
that type Ia supernovae are true standard candles in the infrared
meaning
that our Hubble diagram will be resistant to possible evolution in the
Phillip's
relation over cosmic time. High signal-to-noise measurements of 16
type
Ia events at z~0.4 will be compared with an independent optical Hubble
diagram
from the ESSENCE project to test for a shift in the derived dark
energy
equation of state due to a systematic bias. In
Cycle 15 we obtained
NICMOS
photometry of 8 ESSENCE supernovae and are awaiting template
observations
to place them on the IR Hubble diagram. Here we request another 8
supernovae
be studied in the final season of the ESSENCE search.
Because of
the
bright sky background, H-band photometry of z~0.4 supernovae is not
feasible
from the ground. Only the superb image quality and dark infrared sky
seen
by HST makes this test possible. This experiment may also lead to a
better,
more reliable way of mapping the expansion history of the universe
with
the Joint Dark Energy Mission.
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11198
Title:
Pure
Parallel Imaging in the NDWFS Bootes Field
PI:
Anthony
Gonzalez
PI
Institution:
University
of Florida
The
NOAO Deep-Wide Field Survey (NDWFS) Bootes field is the target of one of
the
most extensive multiwavelength campaigns in astronomy.
In addition to
ground-based
optical and near-infrared imaging, deep radio mapping, and
extensive
spectroscopy, this entire region has been imaged by the Chandra,
Spitzer
(IRAC and MIPS), and GALEX missions.
Robust photometric redshifts
(calibrated
using over 20,000 spectroscopic redshifts) exist for all sources
brighter
than R=24.5 or than 13 uJy at 4.5 microns. To
enhance the value of
this
data set, we propose pure parallel observations for all approved Cycle
16
programs
in this region that lack coordinated parallel observations. The
primary
aim of this program will be to provide a database useful for the broad
range
of science programs underway in this region.
======================================================================
Proposal
Category: GO
Scientific
Category: STAR FORMATION
ID:
11199
Title:
A
Hard Look at Stellar Disks at the Epoch of Planet Formation
PI:
Lee
Hartmann
PI
Institution:
University
of Michigan
We
propose to use HST/ACS/SBC and Chandra/ACIS-S3 to observe the high
energy
fluxes
of 4 stars surrounded by disks in the newly discovered aggregate 25
Ori,
the most populous 10 Myr group known within 500 pc. Our observations
will
cover
the 1-25A and 1250-2000A bandpasses, and will complement our optical and
Spitzer
data for these objects, to provide essential input to physically-
consistent
models of disk structure and chemistry in the age range around 10
Myr,
thought to be a critical period in the planet-forming process. We will
be
able to determine the Ne/O ratio and determine if the anomalous metal
abundances
observed in X-ray spectra of young stars are an evolutionary or an
environmental
effect. Our proposed observations
will double the number of 10
Myr
old accreting stars with known high energy radiation fields, and will be
the
first FUV observations of low mass accreting stars in an OB association.
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11200
Title:
An
Ultraluminous EUV Source?
PI:
Philip
Kaaret
PI
Institution:
University
of Iowa
Ultraluminous
X-ray sources (ULXs) are bright, irregularly variable, non-
nuclear,
X-ray sources with apparent luminosities exceeding the Eddington
limit
for stellar-mass black holes.
There is great interest in ULXs because
they
may represent a new class of black holes with masses intermediate
between
stellar-mass
and supermassive black holes.
Recently, it has been found that
X-ray
emission from the nebula MF 16 in the galaxy NGC 6946, previously
thought
to be an usually luminous supernova remnant, actually arises from an
accreting
compact object. Optical
spectroscopy of nebula shows that it is
powered
via photoionization by an extreme ultraviolet (EUV) source with a
luminosity
exceeding that measured from the X-ray source. If
correct this
would
be the first ultraluminous UV source and may be a 10,000 solar mass
black
hole. We propose an FUV
observation with the ACS/SBC to determine if a
highly
luminous EUV source is indeed, present within MF 16.
======================================================================
Proposal
Category: SNAP
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11201
Title:
Systemic
and Internal motions of the Magellanic Clouds: Third Epoch Images
PI:
Nitya
Kallivayalil
PI
Institution:
Harvard
University
In
Cycles 11 and 13 we obtained two epochs of ACS/HRC data for fields in
the
Magellanic
Clouds centered on background quasars. We used these data to
determine
the proper motions of the LMC and SMC to better than 5% and 15%
respectively.
These are by far the best determinations of the proper motions
of
these two galaxies. The results have a number of unexpected implications
for
the Milky Way-LMC-SMC system. The implied three-dimensional velocities
are
larger
than previously believed, and are not much less than the escape
velocity
in a standard 10^12 solar mass Milky Way dark halo. Orbit
calculations
suggest the Clouds may not be bound to the Milky Way or may just
be
on their first passage, both of which would be unexpected in view of
traditional
interpretations of the Magellanic Stream. Alternatively, the Milky
Way
dark halo may be a factor of two more massive than previously believed,
which
would be suprising in view of other observational constraints. Also, the
relative
velocity between the LMC and SMC is larger than expected, leaving
open
the possibility that the Clouds may not be bound to each other. To
further
verify and refine our results we now request an epoch of WFPC2/PC data
for
the fields centered on 40 quasars that have at least one epoch of ACS
imaging.
We request execution in snapshot mode, as in our previous programs,
to
ensure the most efficient use of HST resources. A third epoch of data of
these
fields will provide crucial information to verify that there are no
residual
systematic effects in our previous measurements. More importantly, it
will
increase the time baseline from 2 to 5 yrs and will increase the number
of
fields with at least two epochs of data. This will reduce our
uncertainties
correspondingly,
so that we can better address whether the Clouds are indeed
bound
to each other and to the Milky Way. It will also allow us to constrain
the
internal motions of various populations within the Clouds, and will
allow
us
to determine a distance to the LMC using rotational parallax.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11202
Title:
The
Structure of Early-type Galaxies:
0.1-100
Effective Radii
PI:
Leon
Koopmans
PI
Institution:
Kapteyn
Astronomical Institute
The
structure, formation and evolution of early-type galaxies is still
largely
an
open problem in cosmology: how
does the Universe evolve from large linear
scales
dominated by dark matter to the highly non-linear scales of galaxies,
where
baryons and dark matter both play important, interacting, roles? To
understand
the complex physical processes involved in their formation
scenario,
and why they have the tight scaling relations that we observe today
(e.g.
the Fundamental Plane), it is critically important not only to
undertstand
their stellar structure, but also their dark-matter distribution
from
the smallest to the largest scales.
Over the last three years the SLACS
collaboration
has developed a toolbox to tackle these issues in a unique and
encompassing
way by combining new non-parametric strong lensing techniques,
stellar
dynamics, and most recently weak gravitational lensing, with high-
quality
Hubble Space Telescope imaging and VLT/Keck spectroscopic data of
early-type
lens systems. This allows us to break degeneracies that are
inherent
to each of these techniques seperately and probe the mass structure
of
early-type galaxies from 0.1 to 100 effective radii. The large dynamic
range
to which lensing is sentive allows us both to probe the clumpy
substructure
of these galaxies, as well as their low-density outer haloes.
These
methods have convincingly been demonstrated, by our team, using smaller
pilot-samples
of SLACS lens systems with HST data.
In this proposal, we
request
observing time with WFPC2 and NICMOS to observe 53 strong lens systems
from
SLACS, to obtain complete multi-color imaging for each system. This
would
bring
the total number of SLACS lens systems to 87 with completed HST imaging
and
effectively doubles the known number of galaxy-scale strong lenses. The
deep
HST images enable us to fully exploit our new techniques, beat down low-
number
statistics, and probe the structure and evolution of early-type
galaxies,
not only with a uniform data-set an order of magnitude larger than
what
is available now, but also with a fully coherent and self-consistent
methodological
approach
======================================================================
Proposal
Category: GO
Scientific
Category: STAR FORMATION
ID:
11203
Title:
A
Search for Circumstellar Disks and Planetary-Mass Companions around
Brown
Dwarfs in Taurus
PI:
Kevin
Luhman
PI
Institution:
The
Pennsylvania State University
During
a 1-orbit program in Cycle 14, we used WFPC2 to obtain the first direct
image
of a circumstellar disk around a brown dwarf. These data have provided
fundamental
new constraints on the formation process of brown dwarfs and the
properties
of their disks. To search for additional direct detections of disks
around
brown dwarfs and to search for planetary-mass companions to these
objects,
we propose a WFPC2 survey of 32 brown dwarfs in the Taurus star-
forming
region.
======================================================================
Proposal
Category: GO
Scientific
Category: STAR FORMATION
ID:
11204
Title:
Imaging
Circumstellar Disks and Envelopes around Proto- Brown Dwarfs
PI:
Kevin
Luhman
PI
Institution:
The
Pennsylvania State University
Using
the Spitzer Space Telescope, we have discovered two young brown dwarfs
with
Class I spectral energy distributions (i.e., proto-brown dwarfs). We
propose
to perform broad-band NICMOS imaging of these Class I brown dwarfs to
spatially
resolve their circumstellar disks and envelopes. If successful,
these
data would comprise the first measurements of this kind for brown dwarfs
and
would provide fundamental constraints on models for the formation of
brown
dwarfs.
======================================================================
Proposal
Category: GO
Scientific
Category: STAR FORMATION
ID:
11205
Title:
The
Effects of Multiplicity on the Evolution of Young Stellar Objects:
A
NICMOS Imaging Study
PI:
James
Muzerolle
PI
Institution:
University
of Arizona
We
propose to use NICMOS to investigate the multiplicity of young stellar
objects
(YSOs) in the Orion B molecular cloud.
Previous observations with the
Spitzer
Space Telescope have revealed a remarkable star forming filament near
the
NGC 2068 reflection nebula. The
population of YSOs associated with the
filament
exhibit a surprisingly wide range of circumstellar evolutionary
states,
from deeply embedded protostars to T Tauri accretion disks. Many of
the
circumstellar disks themselves show evidence for significant dust
evolution,
including grain growth and settling and cleared inner holes,
apparently
in spite of the very young age of these stars. We
will estimate
the
binary fraction of a representative sample of objects in these various
stages
of evolution in order to test whether companions may play a significant
role
in that evolution.
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11206
Title:
At
the cradle of the Milky Way:
Formation
of the most massive field disk galaxies at z>1
PI:
Kai
Noeske
PI
Institution:
University
of California - Santa Cruz
We
propose to obtain 2 orbit WFPC2 F814W images of a sample of the 15 most
massive
galaxies found at $1 < z < 1.3$. These were culled from over
20,000
Keck
spectra collected as part of DEEP and are unique among high redshift
massive
galaxy samples in being kinematically selected.
Through a recent HST
NICMOS-2
imaging program (GO-10532), we have confirmed that these
galaxies
have
regular stellar disks, and their emission line kinematics are not due to
gradients
from merging components. These potentially very young galaxies are
likely
precursors to massive local disks, assuming no further merging. The
proposed
WFPC2 and existing NIC-2 data provide colors, stellar masses, and
ages
of bulge and disk subcomponents,
to assess whether old stellar bulges
and
disks are in place at that time or still being built, and constrain
their
formation
epochs. Finally, this sample will
yield the first statistically
significant
results on the $z > 1$ evolution of the size-velocity-luminosity
scaling
relations, for massive galaxies at different wavelengths, and
constrain
whether this evolution reflects stellar mass growth, or passive
evolution,
of either bulge or disk components.
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11207
Title:
Star
Formation in the Perseus Cluster Cooling Flow
PI:
Robert
O'Connell
PI
Institution:
The
University of Virginia
We
propose to obtain high resolution, UV/optical imaging of the "accretion
populations"
in the massive cooling flow of the Perseus cluster of galaxies.
New
GALEX observations show that the dominant galaxy in this nearby cluster,
NGC
1275, has an extended network of UV-bright populations apparently formed
recently
from the intracluster gas. Cluster
cooling flows are the most
prominent
of the environments where we can readily observe the cycle of gas
accretion,
star formation, and feedback from active nuclei that is thought to
play
a central role in the formation and evolution of galaxies.
Because they
can
be readily age-dated, the accretion populations help to trace the
sequence
of
exchange of material between galaxies and the intracluster medium. The
ACS/SBC
and WFPC2/PC cameras offer the highest spatial resolution and best
panchromatic
performance available to map the spatial and age distribution of
the
accretion populations and their relationship to radio-emitting plasma
and
the
hot intracluster gas.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11208
Title:
The
co-evolution of spheroids and black holes in the last six billion years
PI:
Tommaso
Treu
PI
Institution:
University
of California - Santa Barbara
The
masses of giant black holes are correlated with the luminosities,
masses,
and
velocity dispersions of the bulges of their host galaxies. This
empirical
correlation
of phenomena on widely different scales (from pcs to kpcs)
suggests
that the formation and evolution of galaxies and central black holes
are
closely linked. In Cycle 13, we have started a campaign to map directly
the
co-evolution of spheroids and black-holes by measuring in
observationally
favorable
redshift windows the empirical correlations connecting their
properties.
By focusing on Seyfert 1s, where the nucleus and the stars
contribute
comparable fractions of total light, black hole mass and bulge
dispersion
are obtained from Keck spectroscopy. HST is required for accurate
measurement
of the non stellar AGN continuum, the morphology of the galaxy,
and
the structural parameters of the bulge. The results at z=0.36 indicate a
surprisingly
fast evolution of bulges in the past 4 Gyrs (significant at the
95%CL),
in the sense that bulges were significantly smaller for a given black
hole
mass. Also, the large fraction of mergers and disturbed galaxies (4+2
out
of
20) identifies gas-rich mergers as the mechanisms responsible for bulge-
growth.
Going to higher redshift -- where evolutionary trends should be
stronger
-- is needed to confirm these
tantalizing results. We propose
therefore
to push our investigation to the next suitable redshift window
z=0.57
(lookback-time 6 Gyrs). Fifteen objects are the minimum number required
to
map the evolution of the empirical correlations between bulge properties
and
black-hole mass, and to achieve a conclusive detection of evolution
(>99%CL).
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11209
Title:
Determining
the Structural Parameters of the First Globular Cluster Found to Host
an Black-Hole
X-ray Binary
PI:
Stephen
Zepf
PI
Institution:
Michigan
State University
We
recently published the discovery of the first black hole X-ray binary
in a
globular
cluster. This object is located in a bright globular cluster around
the
Virgo elliptical NGC 4472. Here we propose to obtain HST PC images of
this
black-hole
hosting globular cluster and a sample of other NGC 4472 globulars.
We
will use these data to determine the structural parameters of both the
globular
cluster known to have a black hole and a control sample of other NGC
4472
clusters. This will test recent theoretical predictions how black holes
affect
the structural parameters of globular clusters, and more generally will
allow
for the first time constraints on any relationship between the presence
of
a black hole and the surface brightness profiles of globular clusters.
The
deep
WFPC2 images outside of the galaxy's central regions will also be
invaluable
for studying how the sizes and luminosity function of globular
clusters
depend on distance from the center of the galaxy, and thus address
questions
about the origin of the size differences between metal-rich and
metal-poor
clusters and the shape of the globular cluster luminosity function.
In
addition, parallel NIC3 images will allow the optical to near-infrared
colors
of NGC 4472 globular cluster to be determined over a wide range of
galactocentric
radii.
======================================================================
Proposal
Category: GO
Scientific
Category: COOL STARS
ID:
11210
Title:
The
Architecture of Exoplanetary Systems
PI:
George
Benedict
PI
Institution:
University
of Texas at Austin
Are
all planetary systems coplanar? Concordance cosmogony makes that
prediction.
It is, however, a prediction of extrasolar planetary system
architecture
as yet untested by direct observation for main sequence stars
other
than the Sun. To provide such a
test, we propose to carry out FGS
astrometric
studies on four stars hosting
seven companions. Our understanding
of
the planet formation process will grow as we match not only system
architecture,
but formed planet mass and true distance from the primary with
host
star characteristics for a wide variety of host stars and exoplanet
masses. We propose that a series of FGS
astrometric observations with
demonstrated
1 millisecond of arc per-observation precision can establish the
degree
of coplanarity and component true masses for four extrasolar systems:
HD
202206 (brown dwarf+planet); HD 128311 (planet+planet), HD 160691 = mu
Arae
(planet+planet),
and HD 222404AB = gamma Cephei (planet+star). In each case
the
companion is identified as such by assuming that the minimum mass is the
actual
mass. For the last target, a known stellar binary system, the companion
orbit
is stable only if coplanar with the AB binary orbit.
======================================================================
Proposal
Category: GO
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11211
Title:
An
Astrometric Calibration of Population II Distance Indicators
PI:
George
Benedict
PI
Institution:
University
of Texas at Austin
In
2002 HST produced a highly precise parallax for RR Lyrae. That
measurement
resulted
in an absolute magnitude, M(V)= 0.61+/-0.11, a useful result, judged
by
the over ten refereed citations each year since. It is, however,
unsatisfactory
to have the direct, parallax-based, distance scale of
Population
II variables based on a single star. We propose, therefore, to
obtain
the parallaxes of four additional RR Lyrae stars and two Population II
Cepheids,
or W Vir stars. The Population II
Cepheids lie with the RR Lyrae
stars
on a common K-band Period-Luminosity relation. Using these parallaxes to
inform
that relationship, we anticipate a zero-point error of 0.04 magnitude.
This
result should greatly strengthen confidence in the Population II
distance
scale
and increase our understanding of RR Lyrae star and Pop II Cepheid
astrophysics.
======================================================================
Proposal
Category: SNAP
Scientific
Category: HOT STARS
ID:
11212
Title:
Filling
the Period Gap for Massive Binaries
PI:
Douglas
Gies
PI
Institution:
Georgia
State University Research Foundation
The
current census of binaries among the massive O-type stars is seriously
incomplete
for systems in the period range from years to millennia because the
radial
velocity variations are too small and the angular separations too close
for
easy detection. Here we propose to
discover binaries in this
observational
gap through a Faint Guidance Sensor SNAP survey of relatively
bright targets listed in the Galactic O Star
Catalog. Our primary goal is to
determine
the binary frequency among those in the cluster/association, field,
and
runaway groups. The results will
help us assess the role of binaries in
massive
star formation and in the processes that lead to the ejection of
massive
stars from their natal clusters.
The program will also lead to the
identification
of new, close binaries that will be targets of long term
spectroscopic
and high angular resolution observations to determine their
masses
and distances. The results will
also be important for the
interpretation
of the spectra of suspected and newly identified binary and
multiple
systems.
======================================================================
Proposal
Category: GO
Scientific
Category: COOL STARS
ID:
11213
Title:
Distances
to Eclipsing M Dwarf Binaries
PI:
Gerard
van Belle
PI
Institution:
California
Institute of Technology
We
propose HST FGS observations to measure accurate distances of 5 nearby M
dwarf
eclipsing binary systems, from which model-independent luminosities can
be
calculated. These objects have
either poor or no existing parallax
measurements. FGS parallax determinations for these
systems, with their
existing
dynamic masses determed to better than 0.5%, would serve as model-
independent
anchor points for the low-mass end of the mass-luminosity diagram.
======================================================================
Proposal
Category: GO
Scientific
Category: STAR FORMATION
ID:
11214
Title:
HST/FGS
Astrometric Search for Young Planets Around Beta Pic and AU Mic
PI:
John
Wisniewski
PI
Institution:
NASA
Goddard Space Flight Center
Beta
Pic and AU Mic are two nearby Vega-type debris disk stars.
Both of these
disk
systems have been spatially resolved in exquisite detail, predominantly
via
the ACS coronagraph and WFPC-2 cameras onboard HST.
These images exhibit
a
wealth of morphological features which provide compelling indirect
evidence
that
these systems likely harbor short-period planetary body(ies). We propose
to
use the superlative astrometric capabilities of HST/FGS to directly
detect
these
planets, hence provide the first direct planet detection in a Vega-type
system
whose disk has been imaged at high spatial resolution.
======================================================================
Proposal
Category: GO
Scientific
Category: QUASAR ABSORPTION LINES AND IGM
ID:
11215
Title:
New
Sightlines for the Study of Intergalactic Helium: Dozens of
High-Confidence,
UV-Bright Quasars from SDSS/GALEX
PI:
Scott
Anderson
PI
Institution:
University
of Washington
The
reionization of IGM helium is thought to have occurred at redshifts of
z=3
to
4. Detailed study of HeII Lyman-alpha absorption toward a handful of
QSOs
at
2.7<z<3.3 demonstrated the high potential of such IGM probes, but
the
critically
small sample size limits confidence in cosmological inferences. The
requisite
unobscured sightlines to high-z are extremely rare, but SDSS
provides
5800, z>3.1 QSOs potentially suitable for HeII studies. We've cross-
correlated
SDSS quasars with GALEX UV sources to obtain dozens of new, high
confidence,
candidate sightlines (z=3.1-4.9) potentially useful for detailed
HeII
studies with HST. We propose brief, 2-orbit reconnaissance ACS SBC prism
exposures
toward each of the best dozen new quasars, to definitively verify UV
flux
down to HeII. Our combined SDSS/GALEX selection insures a high
confirmation
rate, as the quasars are already known to be UV bright in GALEX.
Our
program will provide a statistical sample of HeII sightlines extending
to
high
redshift, enabling future long exposure follow-up spectra with the SBC
prism,
or superb quality COS or STIS spectra after SM4. Stacks of our prism
spectra
will also directly yield ensemble information. Ultimately, the new
sightlines
will enable confident measures of the spectrum and evolution of the
ionizing
background, the evolution of HeII opacity, the epoch of helium
reionization,
and the density of IGM baryons.
======================================================================
Proposal
Category: GO
Scientific
Category: AGN/QUASARS
ID:
11216
Title:
Monitoring
the Giant Flare of HST-1 in the M87 Jet
PI:
John
Biretta
PI
Institution:
Space
Telescope Science Institute
As
the nearest galaxy with an optical jet, M87 affords an unparalleled
opportunity
to study extragalactic jet phenomena at the highest resolution.
During
2002, HST and Chandra monitoring of the M87 jet detected a dramatic
flare
in knot HST-1 located ~1" from the nucleus. Its
optical brightness
eventually
increased seventy-fold and peaked in 2005; the X-rays show a
similarly
dramatic outburst. In both bands HST-1 is still extremely bright and
greatly
outshines the galaxy nucleus. To our knowledge this is the first
incidence
of an optical or X-ray outburst from a jet region which is spatially
distinct
from the core source -- this presents an unprecedented opportunity to
study
the processes responsible for non-thermal variability and the X-ray
emission. We propose six epochs of HST/WFPC2 flux
monitoring during Cycle 16,
as
well as seven epochs of Chandra/ACIS observation (5ksec each, six
Chandra
epochs
contemporary with HST). At two of
the HST/WFPC2 epochs we also gather
spectral
information, and at one epoch we will map the magnetic field
structure. The results of this investigation are
of key importance not only
for
understanding the nature of the X-ray emission of the M87 jet, but also
for
understanding flares in blazar jets, which are highly variable, but
where
we
have never before been able to resolve the flaring region in the
optical or
X-rays. These new observations will allow us to
track the decay phase of the
giant
flare, and study smaller secondary flares such as seen late in 2006.
Ultimately
we will test synchrotron emission models for the X-ray outburst,
constrain
particle acceleration and loss timescales, and study the jet
dynamics
associated with this flaring component.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11217
Title:
The
Light Echoes around V838 Monocerotis
PI:
Howard
Bond
PI
Institution:
Space
Telescope Science Institute
V838
Monocerotis, which burst upon the astronomical scene in early 2002, is a
completely
unanticipated new object. It
underwent a large-amplitude and very
luminous
outburst, during which its spectrum remained that of an extremely
cool
supergiant. A rapidly evolving set
of light echoes around V838 Mon was
discovered
soon after the outburst, and quickly became the most spectacular
display
of the phenomenon ever seen. These
light echoes provide the means to
accomplish
three unique types of measurements based on continued HST imaging
during
the event: (1)
Study effects of MHD turbulence at high resolution and
in
3 dimensions; (2) Construct the first unambiguous and fully 3-D map of a
circumstellar
dust envelope in the Milky Way; (3) Study dust physics in a
unique
setting where the spectrum and light curve of the illumination, and the
scattering
angle, are unambiguously known. We have also used our HST data to
determine
the distance to V838 Mon through direct geometric techniques.
Because
of the extreme rarity of light echoes, this is almost certainly the
only
opportunity to achieve such results during the lifetime of HST. We
propose
two visits during Cycle 16, in order to continue the mapping of the
circumstellar
dust and to accomplish the other goals listed above.
======================================================================
Proposal
Category: SNAP
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11218
Title:
Snapshot
Survey for Planetary Nebulae in Globular Clusters of the Local Group
PI:
Howard
Bond
PI
Institution:
Space
Telescope Science Institute
Planetary
nebulae (PNe) in globular clusters (GCs) raise a number of
interesting
issues related to stellar and galactic evolution. The
number of
PNe
known in Milky Way GCs, 4, is surprisingly low if one assumes that all
stars
pass through a PN stage. However,
it is likely that the remnants of
stars
now evolving in Galactic GCs leave the AGB so slowly that any ejected
nebula
dissipates long before the star becomes hot enough to ionize it. Thus
there
should not be ANY PNe in Milky Way GCs--but there are four
======================================================================
Proposal
Category: SNAP
Scientific
Category: AGN/QUASARS
ID:
11219
Title:
Active
Galactic Nuclei in nearby galaxies:
a
new view of the origin of the radio-loud radio-quiet dichotomy?
PI:
Alessandro
Capetti
PI
Institution:
Osservatorio
Astronomico di Torino
Using
archival HST and Chandra observations of 34 nearby early-type galaxies
(drawn
from a complete radio selected sample) we have found evidence that the
radio-loud/radio-quiet
dichotomy is directly connected to the structure of the
inner
regions of their host galaxies in the following sense:
[1] Radio-loud
AGN
are associated with galaxies with shallow cores in their light profiles
[2]
Radio-quiet AGN are only hosted by galaxies with steep cusps. Since the
brightness
profile is determined by the galaxy's evolution, through its merger
history,
our results suggest that the same process sets the AGN flavour. This
provides
us with a novel tool to explore the co-evolution of galaxies and
supermassive
black holes, and it opens a new path to understand the origin of
the
radio-loud/radio-quiet AGN dichotomy.
Currently our analysis is
statistically
incomplete as the brightness profile is not available for 82 of
the
116 targets. Most galaxies were not observed with HST, while in some
cases
the
study is obstructed by the presence of dust features. We here propose to
perform
an infrared NICMOS snapshot survey of
these 82 galaxies. This will
enable
us to i) test the reality of the dichotomic behaviour in a
substantially
larger sample; ii) extend the comparison between radio-loud and
radio-quiet
AGN to a larger range of luminosities.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11220
Title:
Mapping
the FUV Evolution of Type IIn Supernovae
PI:
Jeff
Cooke
PI
Institution:
University
of California - Irvine
We
will use the PR110L prism on the SBC of ACS to map the FUV evolution of
Type
IIn supernovae (SNe).
The main goal of this proposal is to measure the
FUV
continuum, Ly-a emission line flux, and their evolution to (1) quantify
and
interpret Type IIn SN transient event detections at high redshift and
(2)
dramatically
improve current high redshift Type IIn selection criteria. We
show
that the inherent properties of Type IIn SNe facilitate high redshift
detection. We will observe the rest-frame FUV of a
sample of eight 0.02 < z <
0.33
Type IIn SNe to directly measure the survival of Ly-alpha photons in low
redshift
Type IIn SNe environments and extrapolate the results to high
redshift. We will calibrate relationships such as
FUV luminosity vs. emission
line
flux and measure emission line evolution vs. FUV light evolution. The
intent
is to categorize and improve the utility of Type IIn SNe.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11221
Title:
A
Dark Core in Abell 520
PI:
Julianne
Dalcanton
PI
Institution:
University
of Washington
We
have recently disocovered that the rich cluster Abell 520 exhibits truly
extreme
multi-wavelength characteristics. The data indicate that the cluster
is
the site of a major merger. Our weak lensing analysis, based on a deep
CFHT
image,
suggests the presence of a massive dark core that coincides with the
central
X-ray emission peak, while being largely devoid of galaxies. Although
a
displacement between the X-ray gas and the galaxy/dark matter
distribution
may
be expected in a merger (e.g. as in the bullet cluster), the dark matter
peak
without galaxies cannot be easily explained within the current
collisionless
dark matter paradigm. A higher resolution mass map is required
to
make further progress, as it will enable us to examine the detailed
structure
of the dark matter distribution, as well as improve the significance
of
the dark peak. We propose a 3 x 3 WFPC2 mosaic of interlaced images,
where
each
pointing consists of two sets of F814W exposures offset by 5.5 pixels.
This
will precisely pinpoint the locations of the highest lensing peaks,
enhance
the comparison with the Chandra X-ray data, and test physical and
geometrical
models for the spatial and thermal structure of this remarkable
cluster
derived from our suite of gas+dark matter simulations of head-on/off-
axis
cluster mergers.
======================================================================
Proposal
Category: GO
Scientific
Category: AGN/QUASARS
ID:
11222
Title:
Direct
Detection and Mapping of Star Forming Regions in
Nearby, Luminous Quasars
PI:
Michael
Eracleous
PI
Institution:
The
Pennsylvania State University
We
propose to carry out narrow-band emission line imaging observations of
seven
quasars at z=0.05-0.09 with the WFPC2 ramp filters and with the NICMOS
narrow-band
filters. We will obtain images in the [O II], [O III], H-beta, and
Pa-alpha
emission line bands to carry out a series of diagnostic tests aimed
at
detecting and mapping out star-forming regions in the quasar host
galaxies.
This
direct detection of star-forming regions will confirm indirect
indications
for star formation in quasar host galaxies. It will provide a
crucial
test for models of quasar and galaxy evolution, that predict the co-
existence
of starbursts and "monsters" and will solve the puzzle of why
different
indicators of star formation give contradictory results. A secondary
science
goal is to assess suggested correlations between quasar luminosity and
the
size of the narrow-line region.
======================================================================
Proposal
Category: GO
Scientific
Category: COOL STARS
ID:
11223
Title:
The
Key to Understanding RR Lyr Stars:
WFPC2
Observations of a Unique LMC EB with a RR Lyr Component
PI:
Edward
Guinan
PI
Institution:
Villanova
University
We
are proposing HST/WFPC2 2550-10420A multi-band photometry of an
important
"unique"
LMC eclipsing binary with an RR Lyr component. This binary is the
only
bona fide eclipsing binary (EB) with an RR Lyr component. Because of
their
constant mean luminosities (L ~ 45 Lsun; <Mv> ~ +0.5 mag) and
easily
recognizable
light curves, RR Lyr variables have long served as the
"cornerstone"
of the Pop II distance scale in our galaxy and for Local Group
galaxies.
However, in spite of their critical importance to astronomy, there
is
a paucity of fundamental data available for RR Lyr stars. In fact, there
are
no direct measures of their most fundamental properties - such as Mass,
Radius
and Luminosity. The astrophysical and cosmological consequences of
finding
an RR Lyr star in an EB are considerable, because the masses and
absolute
radii of the stars of eclipsing binaries can be determined to within
a
few percent from time-tested analyses of their light and radial velocity
curves.
With accurate temperatures and ISM absorption values, determined from
the
proposed WFPC2 observations, it is possible to determine reliable
stellar
luminosities
and distances. It is for these reasons that we propose WFPC2
observations
of the recently discovered detached LMC eclipsing binary OGLE
J052218.07-692827.4
(<V> ~18.6-mag; <B-V>0 ~+0.27; Porb = 8.9231-d); the RR
Lyr
primary component has a pulsation period of P(RR) = 0.564876-d. This
important
binary star is an integral part of our on-going multi-wavelength
study
of selected eclipsing binaries in nearby galaxies. Three HST/WFPC2
orbits
are requested to determine complementary accurate Teff, log g and ISM
absorption
(A-lambda) for the component stars. These quantities will be
combined
with the fundamental stellar data being determined from our ground-
based
radial velocity and photometric observations. The combined observations
will
yield accurate stellar masses, radii, temperatures and luminosities, as
well
as a direct distance to the binary and LMC-Bar. This RR Lyr/EB thus
offers
the unprecedented opportunity to:
(1)
determine directly (and for the
first
time) the fundamental physical properties (M, R, L) of an RR Lyr star,
(2)
directly calibrate "in situ" the zero-point of the LMC RR Lyr - P -
Mv - Z
relation
and (3) to derive an additional accurate distance to the Bar region
of
the LMC.
======================================================================
Proposal
Category: GO
Scientific
Category: HOT STARS
ID:
11224
Title:
Unraveling
Mira AB Accretion Mysteries
PI:
Margarita
Karovska
PI
Institution:
Smithsonian
Institution Astrophysical Observatory
Wind
accretion is one of the most common yet poorly understood phenomena in
astrophysics.
A key step toward advancing our
understanding of physical
processes
and accretion geometries in wind accreting systems is direct imaging
of
the individual components and mass flows. The nearby symbiotic binary
Mira
AB,
composed of an AGB donor star and an accreting compact companion, is a
unique
target since it can be easily
spatially resolved with the HST, and
thus
serves as a perfect test laboratory for accretion studies in wind
interacting
systems. We propose to carry out
WFPC2 observations of Mira AB
following
the HST and Chandra detections of an unprecedented outburst from the
cool
giant, and the discovery of an accretion stream showing for the first
time
evidence for a direct mass transfer between the components in a wind
accreting
system. High-angular-resolution multiwavelength imaging at UV
/optical
wavelengths will allow us to determine the properties of the ejected
material
as it flows throughout the binary and interacts with the Mira A
circumstellar
material and wind; the physical characteristics of mass transfer
in
this system and especially the role of the accretion stream between
Mira A
and
Mira B; and the response of the system to the increased accretion rate
onto
Mira B following the outburst.
These results will provide crucial inputs
and
quantitative constraints to models of wind interacting systems and will
also
anchor our understanding of accretion processes in a wide range of
interacting
binaries that cannot be currently resolved, including in other
symbiotics
and more exotic systems such as accreting black holes and neutron
stars
in high-mass X-ray binaries.
======================================================================
Proposal
Category: GO
Scientific
Category: AGN/QUASARS
ID:
11225
Title:
The
Wavelength Dependence of Accretion Disk Structure
PI:
C.
Kochanek
PI
Institution:
The
Ohio State University Research Foundation
We
can now routinely measure the size of quasar accretion disks using
gravitational
microlensing of lensed quasars.
The next step to testing
accretion
disk models is to measure the size
of accretion disks as a function
of
wavelength, particularly at the UV
and X-ray wavelengths that should probe
the
inner, strong gravity regime.
Here we focus on two four-image quasar
lenses
that already have optical (R band) and X-ray size measurements
using
microlensing. We will combine the HST observations
with ground-based
monitoring
to measure the disk size as a
function of wavelength from the
near-IR
to the UV. We require HST to
measure the image flux ratios in the
ultraviolet
continuum near the Lyman limit of the quasars. The selected
targets
have estimated black hole masses
that differ by an order of
magnitude,
and we should find wavelength
scalings for the two systems that
are
very different because the Blue/UV
wavelengths should correspond to parts
of
the disk near the inner edge for
the high mass system but not in the
low
mass
system. The results will be
modeled using a combination of simple thin
disk
models and complete relativistic disk models. While requiring only 18
orbits,
success for one system requires observations
in both Cycles 16 and
17.
======================================================================
Proposal
Category: GO
Scientific
Category: SOLAR SYSTEM
ID:
11226
Title:
Hubble
Investigation of Comet 8P/Tuttle
PI:
Philippe
Lamy
PI
Institution:
Laboratoire
d'Astrophysique de Marseille
Comet
8P/Tuttle is a returning nearly isotropic comet (NIC) with an
outstanding
apparition in cycle 16, passing within 0.25 AU of the Earth. We
propose
a 12-orbit Hubble investigation that will allow us to determine the
size,
shape, rotational period, and color (UBVRI) of 8P, thereby providing the
most
detailed view of a NIC nucleus since the spacecraft flyby of 1P/Halley
in
1986.
The return of 8P is a rare opportunity, and we expect many other
observatories,
including Spitzer, to be investigating this comet. Combining
the
Hubble results with those from
other observatories should yield a
comprehensive
picture of this NIC that can be compared to the detailed data
collected
on ecliptic comets (ECs) during the past 3 decades. The differences
and
similarities between NICs and ECs should yield valuable insights into
the
origin
and evolution of comets.
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11227
Title:
The
orbital period for an ultraluminous X-ray source in NGC1313
PI:
Jifeng
Liu
PI
Institution:
Smithsonian
Institution Astrophysical Observatory
The
ultraluminous X-ray sources (ULXs) are extragalactic point sources with
luminosities
that exceed the Eddington luminosity for conventional stellar-
mass
black holes by factors of 10 - 100.
It has been hotly debated whether
the
ULXs are just common stellar-mass black hole sources with beamed
emission
or
whether they are sub-Eddington sources that are powered by the
long-sought
intermediate
mass black holes (IMBH). To firmly
decide this question, one
must
obtain dynamical mass measurements through photometric and spectroscopic
monitoring
of the secondaries of these system.
The crucial first step is to
establish
the orbital period of a ULX, and arguably the best way to achieve
this
goal is by monitoring its ellipsoidal light curve.
The extreme ULX
NGC1313
X-2 provides an outstanding target for an orbital period determination
because
its relatively bright optical counterpart (V = 23.5) showed a 15%
variation
between two HST observations separated by three months.
This level
of
variability is consistent with that expected for a tidally distorted
secondary
star. Here we propose a set of 20
imaging observations with
HST/WFPC2
to define the orbital period. This
would be the first photometric
measurement
of the orbital period of a ULX binary. Subsequently, we will
propose
to obtain spectroscopic observations to obtain its radial velocity
amplitude
and thereby a dynamical estimate of its mass.
======================================================================
Proposal
Category: GO
Scientific
Category: STAR FORMATION
ID:
11228
Title:
Extrasolar
Planet XO-2b
PI:
Peter
McCullough
PI
Institution:
Space
Telescope Science Institute
We
propose observations of the newly discovered extrasolar planet XO-2b and
its
twin star XO-2. When combined with the transit light curve, the FGS-
derived
parallax will constrain the stellar mass of the host star XO-2. From
the
high signal-to-noise near-IR time series resulting from NICMOS grism
spectroscopy,
we will refine the system parameters, in particular radii of the
star
and planet. From the same data, we will search for evidence of water
vapor
in the atmosphere via transmission spectroscopy. Differential
observations
with NICMOS in the spectroscopic mode will be used to search for
the
small spectral changes that occur during planetary transits resulting
from
absorption
of stellar light as it passes through the planetary atmosphere.
Water
is an important constituent, the detection of which would provide
information
on Oxygen, and it has a convenient strong band well-positioned for
NICMOS.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11229
Title:
SEEDS:
The
Search for Evolution of Emission from Dust in Supernovae with HST and
Spitzer
PI:
Margaret
Meixner
PI
Institution:
Space
Telescope Science Institute
The
role that massive stars play in the dust content of the Universe is
extremely
uncertain. It has long been
hypothesized that dust can condense
within
the ejecta of supernovae (SNe), however there is a frustrating
discrepancy
between the amounts of dust found in the early Universe, or
predicted
by nucleation theory, and inferred from SN observations. Our SEEDS
collaboration
has been carefully revisiting the observational case for dust
formation
by core-collapse SNe, in order to quantify their role as dust
contributors
in the early Universe. As dust
condenses in expanding SN ejecta,
it
will increase in optical depth, producing three simultaneously
observable
phenomena: (1) increasing optical extinction; (2) infrared
(IR) excesses; and
(3)
asymmetric blue-shifted emission lines. Our SEEDS collaboration recently
reported
all three phenomena occuring in SN2003gd, demonstrating the success
of
our observing strategy, and permitting us to derive a dust mass of up to
0.02
solar masses created in the SN. To advance our understanding of the
origin
and evolution of the interstellar dust in galaxies, we propose to use
HST's
WFPC2 and NICMOS instruments plus Spitzer's photometric instruments to
monitor
ten recent core-collapse SNe for dust formation and, as a bonus,
detect
light echoes that can affect the dust mass estimates. These space-borne
observations
will be supplemented by ground-based spectroscopic monitoring of
their
optical emission line profiles. These observations would continue our 2-
year
HST and Spitzer monitoring of this phenomena in order to address two key
questions: Do all SNe produce
dust? and How much dust do they produce?
As all
the
SN are witin 15 Mpc, each SN stands an excellent chance of
detection with
HST
and Spitzer and of resolving potential light echoes.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM IN EXTERNAL GALAXIES
ID:
11230
Title:
HST
FUV Observations of Brightest Cluster Galaxies: The
Role of Star Formation in Cooling Flows and BCG Evolution
PI:
Christopher
O'Dea
PI
Institution:
Rochester
Institute of Technology
The
intracluster medium (ICM) now
appears to be a very dynamic place where
heating
and cooling processes vie for dominance and an uneasy equilibrium is
maintained.
Since these same processes may operate during the process of
galaxy
formation, the centers of clusters of galaxies provide low redshift
laboratories
for studying the critical processes involved in galaxy formation
and
black hole growth. At the present time, the main questions are (1) How
much
gas is cooling out of the ICM? (2) How much star formation is ongoing?
(3)
What is the impact of the gas and star formation on the central BCG? In
order
to measure the current star formation in BCGs we have undertaken a
program
of Spitzer IRAC and MIPS observations. We are in process of obtaining
observations
of a sample of Brightest Cluster Galaxies in 70 clusters selected
from
the ROSAT all sky survey. In about 25% of the sources observed so far,
we
detect
a mid-IR excess which we attribute to dust heated by star formation. We
propose
to obtain ACS/SBC observations of the Lyman Alpha emission line and
the
adjacent FUV continuum in 7 BCGs which are in cooling core clusters of
galaxies
and have a large mid-IR excess. We also propose WFPC2 F606W
observations
of the two clusters without high resolution imaging to allow us
to
image the dust on the same scale as the Far UV continuum. The FUV will
allow
us to confirm the presense of ongoing starformation in these BCGs and
will
allow us to rule out an AGN as the dominant contributer to the mid-IR.
The
morphology and spatial extent of the young stars and the heated dust and
CO
will constrain the spatial scale over which star formation occurs and
thus
where
the cooling gas is deposited. The
combination of our FUV and IR
observations
will allow us to estimate the star formation rates which
must
balance
the rate at which cold gas is deposited in the BCG. Our proposed FUV
observations
will produce unique information about the cooling gas, the true
mass
accretion rates, and the star formation rates in BCGs and its effect on
the
galaxy.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11231
Title:
Calibration
of the WFPC2 HeII and [SII] Filters.
PI:
C.
O'Dell
PI
Institution:
Vanderbilt
University
Observations
of NGC 6720 (the Ring Nebula) will be used to determine the
calibration
constants for the important emission-line filters that isolate
nebular
HeII (F469N) and [SII] (F673N) emission. The pre-launch calibrations
are
inadequate because of possible temporal changes and the fact that these
interference
filters are used in a different configuration from that of the
ground
calibration. The Ring Nebula is a nearly ideal reference source as
multiple
2.4"x4.0" samples have been accurately measured spectro-
photometrically
and five of the six samples can be imaged with one pointing of
the
HST. The method of derivation of
the calibration constants will be the
same
as previously employed to calibrate the primary emission-line filters
for
the
WFPC2 (F487N, F502N, F656N, F658N) and ACS (F502N, F658N, F660N) using
the
Orion
Nebula as a reference source. However, Orion cannot be used for this
calibration
because the targeted lines are weak ([SII]) or absent (HeII) and
the
scattered-light continuum is strong. The Ring Nebula has strong HeII
emission
in its middle, strong [SII] emission in its main ring, and a weak
(atomic
only) continuum.
======================================================================
Proposal
Category: GO
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11232
Title:
Determination
of Angular Expansion Velocities in the Ring Nebula
PI:
C.
O'Dell
PI
Institution:
Vanderbilt
University
The
Ring Nebula (NGC 6720) represents an important stage in the evolution of
planetary
nebulae, being large enough that it has entered the post fast-wind
stage
yet has not reached the late ballistic phase of objects like the Helix
Nebula.
Understanding this nebula well presents the opportunity to determine
how
nebulae transition from their creation phase into the form they have as
their
material enters the interstellar medium.
A recent study based on
ground-based
spectroscopy has derived a new and accurate model for the Ring
Nebula.
A well defined characteristic of this model is that it predicts a
tangential
velocity of 20 km/s whereas the application of its quite uncertain
trigonometric
parallax distance of 700 (+450/-200) pc with the angular
expansion
velocity determined from HST observations with a 2 year time base
indicates
a tangential velocity of 69 (+45/-20) km/s. This disagreement
indicates
that either the distance is even more uncertain than thought or that
the
earlier angular velocity is incorrect.
We propose to make a new set of
observations
of the Ring Nebula in the diagnostic emission line filters F469N
(HeII),
F502N ([OIII]), and F658N ([NII]) that will produce much more accurate
angular
velocities than the previous study by having a time base of 8.8 years
and
imaging the nebula entirely within a single CCD of the WFPC2. The
primary
result
from this study will be an accurate distance to this important nebula
and
from this to be able to use this object to refine our picture of how
planetary
nebulae evolve during middle-age.
======================================================================
Proposal
Category: GO
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11233
Title:
Multiple
Generations of Stars in Massive Galactic Globular Clusters
PI:
Giampaolo
Piotto
PI
Institution:
Universita
di Padova
This
is a follow-up to recent HST imaging of NGC 2808, which discovered that
its
main sequence is triple, with three well-separated parallel branches
(Fig.~1). Along with the double MS of Omega
Centauri, this challenges the
long-held
paradigm that globular clusters are simple, single stellar
populations. The cause of this main sequence
multiplicity in both clusters is
likely
to be differences in helium abundance, which could play a fundamental
role
in the understanding of stellar populations. We propose to image seven
more
of the most massive globular clusters, to examine their main sequences
for
indications of splitting.
======================================================================
Proposal
Category: GO
Scientific
Category: HOT STARS
ID:
11234
Title:
A
Brief Revisit of the Crab
PI:
Roger
Romani
PI
Institution:
Stanford
University
We
propose using WFPC2 to obtain continuum-dominated images of the Crab
pulsar
and
environs closely duplicating archival exposures from 1994 and 1995. By
matching
the archival data we can realize ~3mas precision astrometry with a
minimum
of systematic effects over a maximum (~13.5y) baseline.
This
determines
the Crab proper motion to better than 0.3mas/yr (3km/s) accuracy
and
measures its position angle to better than 1.5degrees, i.e. reducing the
errrors
of the best present (HST archive) measurement by a factor of three.
Most
importantly, this provide a nearly systematic-free result. This proper
motion
measurement would match the precision of the CXO-measured angular
momentum
vector. Comparison of these vectors is the foundation of an effort to
understand
the physical origin of the large momentum kick at pulsar birth.
======================================================================
Proposal
Category: GO
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11235
Title:
HST
NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies in
the Local
Universe
PI:
Jason
Surace
PI
Institution:
California
Institute of Technology
At
luminosities above 10^11.4 L_sun, the space density of far-infrared
selected
galaxies exceeds that of optically selected galaxies. These `luminous
infrared
galaxies' (LIRGs) are primarily interacting or merging disk galaxies
undergoing
enhanced star formation and Active Galactic Nuclei (AGN) activity,
possibly
triggered as the objects transform into massive S0 and elliptical
merger
remnants. We propose NICMOS NIC2 imaging of the nuclear regions of a
complete
sample of 88 L_IR > 10^11.4 L_sun luminous infrared galaxies in the
IRAS
Revised Bright Galaxy Sample (RBGS: i.e.,
60 micron flux density > 5.24
Jy).
This sample is ideal not only in its completeness and sample size, but
also
in the proximity and brightness of the galaxies. The superb sensitivity
and
resolution of NICMOS NIC2 on HST enables a unique opportunity to study
the
detailed
structure of the nuclear regions, where dust obscuration may mask
star
clusters, AGN and additional nuclei from optical view, with a resolution
significantly
higher than possible with Spitzer IRAC. This survey thus
provides
a crucial component to our study of the dynamics and evolution of IR
galaxies
presently underway with Wide-Field, HST ACS/WFC and Spitzer IRAC
observations
of these 88 galaxies. Imaging will be done with the F160W filter
(H-band)
to examine as a function of both luminosity and merger stage (i) the
luminosity
and distribution of embedded star clusters, (ii) the presence of
optically
obscured AGN and nuclei, (iii) the correlation between the
distribution
of 1.6 micron emission and the mid-IR emission as detected by
Spitzer
IRAC, and (iv) the evidence of bars or bridges that may funnel fuel
into
the nuclear region. The NICMOS data, combined with the HST ACS, Spitzer,
and
GALEX observations of this sample, will result in the most comprehensive
study
of merging and interacting galaxies to date.
======================================================================
Proposal
Category: GO
Scientific
Category: COSMOLOGY
ID:
11236
Title:
Did
Rare, Large Escape-Fraction Galaxies Reionize the Universe?
PI:
Harry
Teplitz
PI
Institution:
California
Institute of Technology
Lyman
continuum photons produced in massive starbursts may have played a
dominant
role in the reionization of the Universe. Starbursts are important
contributors
to the ionizing metagalactic background at lower redshifts as
well.
However, their contribution to the background depends upon the fraction
of
ionizing radiation that escapes from the intrinsic opacity of galaxies
below
the Lyman limit. Current surveys suggest that the escape fraction is
close
to zero in most galaxies, even among young starbursts, but is large in
15-25%
of them. Non-uniform escape
fractions are expected as a result of
violent
events creating clear paths in small parts of galaxies.
The number of
galaxies
observed with high escape fraction will result from the combination
of
the intrinsic number with clear lines of sight and their orientation
with
respect
to the observer. We propose
to measure the fraction of escaping
Lyman
continuum radiation in a large sample (47) of z~0.7 starbursts in the
COSMOS
field. These compact UV-lumnious
galaxies are good analogs to high
redshift
LBGs. Using the SBC/PR130L we can quickly (1-4 orbits) detect
relative
escape fractions (f_LC/f_1500) of 25% or more. This
will be the
first
measurement of the escape fraction in sources between z=1 and the local
universe.
We expect ~10 detections.
Stacking will set limits of <4%
on the
relative
escape fraction in the rest. We
will correlate the LC detections
with
the properties of the galaxies. By
targetting z~0.7 in COSMOS, we will
have
tremendous ancillary information on those sources.
A non-detection in
all
sources would be significant (99% confidence). This
would imply that QSOs
provide
the overwhelming majority of ionizing radtion at z<1, requiring
substantial
evolution in the processes within Lyman break galaxies which allow
large
escape fractions at high redshift.
======================================================================
Proposal
Category: GO
Scientific
Category: AGN/QUASARS
ID:
11237
Title:
The
origin of the break in the AGN luminosity function
PI:
Lutz
Wisotzki
PI
Institution:
Astrophysikalisches
Institut Potsdam
We
propose to use NICMOS imaging to measure rest-frame optical luminosities
and
morphological properties of a complete sample of faint AGN host galaxies
at
redshifts z ~ 1.4. The targets are drawn from the VLT-VIMOS Deep Survey,
and
they constitute a sample of the lowest luminosity type 1 AGN known at z
>
1.
The spectroscopically estimated black hole masses are up to an order of
magnitude
higher than expected given their nuclear luminosities, implying
highly
sub-Eddington accretion rates. This exactly matches the prediction made
by
recent theoretical models of AGN evolution, according to which the faint
end
of the AGN luminosity function is populated mainly by big black holes
that
have
already exhausted a good part of their fuel. In
this proposal we want to
test
further predictions of that hypothesis, by focussing on the host galaxy
properties
of our low-luminosity, low-accretion AGN. If the local ratio
between
black hole and bulge masses holds at least approximately at these
redshifts,
one expects most of these low-luminosity AGN to reside
in fairly
big
ellipticals with stellar masses around and above 10^11 solar masses (in
contrast
to the Seyfert phenomenon in the local universe). With NICMOS imaging
we
will find out whether that is true, implying also a sensitive test for
the
validity
of the M_BH/M_bulge relation at z ~ 1.4.
======================================================================
Proposal
Category: AR
Scientific
Category: COOL STARS
ID:
11238
Title:
Searching
For Unresolved Binary Brown Dwarfs Using Point Spread Functions
PI:
Jacob
Albretsen
PI
Institution:
Brigham
Young University
There
currently are objects of L and T spectral type with errors in their
classification
of +/- 1 to 2. Metallicity and
gravitational differences have
accounted
for some of these discrepancies, and recent studies have shown
unresolved
binary brown dwarfs may offer some explanation as well.
However
limitations
in technology and resources make it difficult to clearly resolve
an
object that may be binary in nature.
It has been shown that using model
point-spread
functions for single and binary sources have been able to
identify
statistically strong binary candidates from images that are
apparently
unresolved. The HST archive
contains numerous observations of
brown
dwarfs from NICMOS that have never been rigorously analyzed for binary
properties. Results from for this archive
proposal will help determine if
there
really is an increase in binary brown dwarfs in the L/T transition and
identify
potential candidates for future observations to determine orbital
information.
======================================================================
Proposal
Category: AR
Scientific
Category: COOL STARS
ID:
11239
Title:
Identifying
Atomic and Molecular Absorption in an Extrasolar Planet Atmosphere
PI:
Travis
Barman
PI
Institution:
Lowell
Observatory
A
significant amount of Hubble Space Telescope time has been spent
observing a
normal
bright main-sequence star, HD209458, which happens to also be home to
one
of the few transiting extrasolar planets.
Time-series spectroscopic data
taken
with STIS and ASC are available in the archive covering numerous
planetary
transits over the past 7 years.
These data have allowed the
discovery
of sodium absorption in HD209458b's atmosphere along with a
hydrogen-rich
extended exosphere. There is great
potential for significant
new
discoveries with these data that could further constrain the chemical
composition
and chemical evolution of HD209458b.
This proposal outlines steps
toward
improving our understanding of the chemical composition of extrasolar
giant
planet atmospheres by developing new models for the wavelength-dependent
eclipse
depth that may be directly compared to archival Hubble Space Telescope
observations.
======================================================================
Proposal
Category: AR
Scientific
Category: STAR FORMATION
ID:
11240
Title:
Mass
Loss From Hot Jupiters
PI:
Eugene
Chiang
PI
Institution:
University
of California - Berkeley
Photoionization
heating from UV radiation incident on the atmospheres of hot
Jupiters
drives planetary mass loss in the form of hydrodynamic winds. HST
STIS
observations of HD 209458b, the first hot Jupiter discovered to transit
its
host star, have confirmed that the planet is losing atomic hydrogen
(Vidal-Madjar
et al. 2003) and have suggested that it may be losing OI and CII
(Vidal-Madjar
et al. 2004). These observations,
which can be repeated with
the
advent of the HST Cosmic Origins Spectrograph (COS), do not necessarily
imply
loss of gas at a rate large enough to significantly reduce the mass of
the
planet. HST STIS observations
indicating a population of hydrogen in the
n=2
state constrain the structure of the planet's escaping atmosphere
(Ballester
et al.~2007). We propose to
construct a model of mass loss from
hot
Jupiter atmospheres, including realistic heating and cooling, ionization
balance,
tidal gravity, and pressure-confinement by the stellar wind. We have
already
constructed a model that resolves the atmosphere's transition from
atomic
to ionized hydrogen. In our
proposed work, we plan to also resolve the
transition
from molecular to atomic hydrogen.
We will employ ray-tracing
through
our model to explain the HST STIS detections of Lyman alpha and Balmer
continuum
absorption by neutral hydrogen in an extended atmosphere around HD
209458b,
and we will experiment with metal chemistry and vertical mixing in an
attempt
to reproduce the HST STIS measurement of OI and CII.
Our work will
provide
predictions for future COS measurements.
We will infer the correct
mass
loss rate implied by the Vidal-Madjar et al. (2003) observation and
search
for new observational diagnostics of hot Jupiter atmospheres.
======================================================================
Proposal
Category: AR
Scientific
Category: COSMOLOGY
ID:
11241
Title:
IR
Background Fluctuations in NICMOS Ultra and Hubble Fields and the
Surface
Density of First-Light Galaxies
PI:
Asantha
Cooray
PI
Institution:
University
of California - Irvine
We
propose an archival analysis of F160W and F110W NICMOS Ultra Deep Field
(NUDF)
and Hubble Deep Field North (HDFN) data, combined with deep HST ACS
images
of the same field, to measure clustering of unresolved IR background
(IRB)
present in "empty"
pixels. These clustering measurements will be used
to
study any indications for the presence of an unresolved, diffuse IR
background
from redshifts related to reionization and associated with
redshifted
UV emission from first-light galaxies and Lyman-alpha emission from
recombinations
in surrounding HII halos. The IR background from these sources
are
expected to peak at wavelengths between 1 and 2 microns and it's
fluctuations
have a clustering spectrum distinctively different from that of
low-redshift
faint galaxies. We will account for the confusion from latter
with
ACS detections of faint blue optical galaxies with no IR counterparts in
NICMOS
images. We will cross-correlate unresolved IR fluctuations between
F110W
and F160W images of the same field to determine any wavelength
dependence
of the IR background and to separate various noise and systematic
effects
which are not common to both passbands. We will simulate to estimate
the
noise floor generated by residual flat-field errors and the pedestal
effect
involving varying bias in different quadrants of the NICMOS array. For
IR
anisotropy power spectrum measurements, we will borrow and implement
well
established
techniques used with cosmic microwave background (CMB) anisotropy
maps
by the CMB community. At a wavelength of 1.25 microns, DIRBE indicates a
total
IRB intensity of 54 +/- 17 nW/m^2/sr or 28 +/- 15 nW/m^2/sr, while about
8
nW/m^2/sr comes from known galaxy counts. Our clustering measurements,
combined
with analytical and numerical models, will lead to a detection of the
total
IRB intensity from first-light galaxies containing Pop III stars during
reionization
as low as 3 nW/m^2/sr. A direct estimate on the integrated
intensity,
and thus the surface density of first-light galaxies, from
unresolved
IR fluctuations has strong consequences for imaging searches for
high-redshift
Lyman-alpha emitters and for models of galaxy formation and
evolution.
======================================================================
Proposal
Category: AR
Scientific
Category: COSMOLOGY
ID:
11242
Title:
IR
Background Intensity, Anisotropy, and Lyman-alpha Sources in Large
Volume
Simulations of Reionization
PI:
Asantha
Cooray
PI
Institution:
University
of California - Irvine
We
propose to analyze properties of the UV photon background emitted by
reionizing
sources redshifted to IR wavelngths today in a set of large volume,
(100
Mpc)^3, high resolution
simulations (24 billion particles) of the cosmic
reionization
process. Using these cosmological simulations, we will establish,
for
the first time, the expected IR
background intensity at wavelengths
between
~1 micron and ~4 microns as well as the anisotropy power spectrum of
fluctuations
observable with NICMOS F110W/F160W bands and WFC3 IR bands. The
new
hybrid code for reionization simulations developed at Princeton by CoIs
Cen
& Trac includes an adaptive ray tracing algorithm for radiative
transfer
of
ionizing photons from first-light galaxies containing both population II
and
population III stars. Fluctuation studies of the unresolved intensity in
deep
IR images, including those with NICMOS, have shown an excess anisotropy
contribution
above noise when resolved sources down to very faint flux levels
are
masked out. This excess has been described as a signature of first
galaxies
containing Pop III stars. While fluctuation measurements have not
conclusively
established the presence of Pop III stars, we
do expect
unresolved
IR background to fluctuate due to clustering of first-light
sources. Given differences in model assumptions,
analytical predictions on
the
fluctuation strength vary widely in the literature, while numerical
simulations
of reionization have not been used to study IR background
statistics.
These will be compared to existing measurements and to establish
requirements
(depth, area) for a WFC3 survey to measure statistics of first
galaxies.
We will investigate how color information, in terms of fluctuation
amplitude
ratios of IR bandpasses of NICMOS and WFC3, can be used to study the
redshift
duration of reionization. Simulations will be used to update number
counts,
luminosity functions, and clustering of Lyman-alpha sources, and to
compare
with recent measurements of Lyman-alpha source statistics at z > 6 by
taking
into account of sample variance within the ~1 degree^2 field provided
by
simulations. Simulations will also be used to study the transition
between
dominant
Pop III to dominant Pop II starformation, and any observable
signatures.
In addition to results in peer-reviewed publications, simulation
outputs
in the form of Lyman-alpha source maps at various passbands of both
NICMOS
and WFC3 will be made available publicly on the web within a year of
beginning
this research.
======================================================================
Proposal
Category: AR
Scientific
Category: AGN/QUASARS
ID:
11243
Title:
Determining
the Inclinations of AGN using Narrow-Line Region Kinematics
PI:
D.
Crenshaw
PI
Institution:
Georgia
State University Research Foundation
We
will determine the inclinations of the AGN in 36 Seyfert galaxies with
STIS
G430M
and/or G430L long-slit spectra, by measuring radial velocities as a
function
of position in their narrow-line regions (NLRs) and generating
kinematic
models to match the observed radial velocities. Our previous studies
of
three Seyfert galaxies with STIS show that the kinematics of their NLRs
are
dominated
by radial outflow, and that simple biconical outflow models can be
used
to derive the inclination of the bicone axis, and hence the obscuring
torus,
with respect to our line of sight. The inclinations will be compared
with
those from other techniques (water masers, broad Fe K-alpha profiles) to
test
for discrepancies and identify possible misalignments between the
accretion
disk, torus, and/or host galaxy. More importantly, our results will
provide
the foundation for future studies that investigate the dependence of
observed
properties (e.g., SEDs, absorbing columns, broad-line widths) on
inclination,
which is vital for understanding the physics of AGN.
======================================================================
Proposal
Category: AR
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11244
Title:
WFPC2
CTE and Photometric Zero Points
PI:
Andrew
Dolphin
PI
Institution:
Raytheon
Company
With
charge-transfer efficiency (CTE) losses of several tenths of a magnitude
in
many current exposures, the accuracy of CTE corrections is a limiting
factor
in the accuracy of photometry that can be obtained with WFPC2.
However,
the CTE corrections in common use are five years old, and thus
corrections
for CTE loss on current observations are made with the dangerous
assumption
that CTE loss has continued growing over the past five years at the
rate
it grew for the instruments first eight years of service.
The
uncertainty
caused by this assumption implies that the use of these old CTE
corrections
is the dominant error source in many WFPC2 images, and will become
even
worse in Cycle 16 as the extrapolation increases. This
proposal seeks to
remedy
this situation by undertaking an examination of CTE using data of the
Omega
Cen calibration field obtained over the entire lifetime of WFPC2. The
methodology
has been proven to produce accurate CTE corrections (indeed, they
are
the recommended corrections in the WFPC2 handbook and online CTE
calculator).
======================================================================
Proposal
Category: AR
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11245
Title:
Mining
the Rich Archive for 47 Tucanae
PI:
Peter
Edmonds
PI
Institution:
Eureka
Scientific Inc.
We
propose to capitalise on the extensive set of scientific and calibration
observations
of the remarkable globular cluster 47 Tuc. The
chief goals are:
(1)
to address key questions about the binaries found in this massive
cluster,
including
studies of cataclysmic variables (CVs), low-mass X-ray binaries
(LMXBs),
millisecond pulsars (MSPs) and chromospherically active binaries, and
(2)
to study a dynamically important but thus far neglected class of
binaries,
containing
subgiant and giant stars. We plan to make the most extensive
analysis
to date of long-term variability in globular cluster binaries,
including
searches for dwarf nova outbursts, high and low states and periodic
variations
for CVs; study accretion rate changes for LMXBs; study active
binaries
that appear to undergo coronal mass ejections; identify the nature of
two
binaries that experience incredibly bright X-ray flares; confirm new
candidates
of rare MSPs with main sequence companions; search for optical IDs
of
unidentified Chandra sources. This is the richest population of binaries
known
in any globular cluster and the complete archival dataset is unlikely to
be
rivaled for many years. These
studies will add to our understanding of
this
important crash-test laboratory and have broader implications for
stellar
dynamics,
stellar and binary evolution and globular cluster evolution.
======================================================================
Proposal
Category: AR
Scientific
Category: COSMOLOGY
ID:
11246
Title:
Evolution
in the Dark Matter Properties of Strong Lenses through Weak Lensing
PI:
Christopher
Fassnacht
PI
Institution:
University
of California - Davis
To
fully exploit the information on the dark matter mass profiles of
galaxies
gained
from weak lensing and to tie this to their inner regions where baryons
play
an important role, we propose to investigate a special sample of
galaxies,
namely strong gravitational lenses.
These systems are excellent
targets
for weak lensing studies because the Einstein ring radii provide a
direct
measurement of the projected mass at very small scales -- information
that
is not available for most galaxy samples.
This project is especially
well
suited for an archival program because nearly every strong lens system
has
been imaged with HST, and the data are public. What
makes this project
stand
out is that we can compare strong lens samples at moderate redshift
(median
z ~ 0.6) and lower redshift (median z ~ 0.2) and can, thus, use the
full
power of combining strong and weak lensing in our investigation of
evolutionary
effects over this timescale. We
will use our samples to (1)
measure
the average mass profile of the sample to R ~ 300 kpc/h, (2) quantify
the
evolution of stellar mass and virial mass-to-light ratios, and (3)
investigate
whether the ``bulge-halo conspiracy'', whereby the CDM profiles of
galaxies
are NFW but the total (baryonic plus CDM) mass profile are isothermal
out
to ~ 300 kpc/h, is in place at higher redshifts.
======================================================================
Proposal
Category: AR
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11247
Title:
Light
Element Nucleosynthesis through Measurements of Interstellar Boron
PI:
Steven
Federman
PI
Institution:
University
of Toledo
With
the aim of identifying the sources of light element
(Li, Be, B, and F)
synthesis,
we propose a survey of interstellar boron. The B II line at 1362 A
will
be used to extract the B column density along more than fifty sight
lines,
many of which are associated with regions of massive star formation
shaped
by core-collapse supernovae (SNe II).
HST spectra are the only means
for
determining the elemental B abundance for sources outside the solar
system.
The survey will contain directions that are both molecule poor and
molecule
rich, thereby enabling us to examine the overall level of boron
depletion
onto grains as a function of gas density. Both the average density
of
neutral material along the line of sight and the density inferred from
the
fraction
of neutral gas in molecular form will be incorporated into the
analysis.
We will seek sight lines with B abundances enhanced over the value
seen
in regions with the least depletion; such enhancements mainly arise from
recent
production of B-11. The boron column density, with the fluorine column
density
obtained from archival FUSE spectra of the F I line at 954 A, will
give
the B/F abundance ratio. This ratio is a diagnostic of the importance of
neutrino-induced
spallation in SNe II in effecting synthesis of B and F, a
process
for which direct observational evidence is still lacking.
======================================================================
Proposal
Category: AR
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11248
Title:
The
Local Environments of Supernovae
PI:
Alex
Filippenko
PI
Institution:
University
of California - Berkeley
The
locations of supernovae (SNe) in the local stellar and gaseous
environment
in
galaxies, as measured in high spatial resolution WFPC2 and ACS images,
contain
important clues to their progenitor stars. They provide accurate
determinations
of any association of SNe with H II regions or star clusters.
Since
multi-filter observations are generally available, we can determine the
local
stellar population, setting constraints on the mass of the progenitor;
we
can also search for possible attenuation of the SN by dust in the host
galaxy
by studying the colors of the stars in its environment. By checking the
fields
for background sources, we can correct the existing SN light curves and
luminosities
if necessary. When a SN has been observed incidentally,
information
can be gained on its optical and UV emission. Deep HST images can
be
used to find light echoes of SNe, as well as recover SNe interacting
with
circumstellar
material at very late times. A direct search for the progenitor
stars
of SNe can be made in pre-existing HST images of their locations; as the
number
of archival HST images steadily increases, along with the number of
newly
discovered SNe, positive identifications become progressively more
likely.
In Cycle 16, we plan to extend our successful work from previous
cycles.
This proposal is complementary to our Cycle 16 survey proposal, whose
primary
purpose is to obtain late-time photometry of SNe. It is also
complementary
to our Cycle 16 ToO proposal, which is designed to pinpoint the
locations
of recent SNe to help determine their progenitor stars.
======================================================================
Proposal
Category: AR
Scientific
Category: ISM IN EXTERNAL GALAXIES
ID:
11249
Title:
Dust
Enhancement of the Lyman Alpha Equivalent Width at z ~ 4.5 in the CDF-S
PI:
Steven
Finkelstein
PI
Institution:
Arizona
State University
We
propose to study high-redshift Lyman alpha emitting galaxies in order to
discover
the true nature of their large equivalent widths. Lyman
alpha
galaxies
are interesting to study because they are very faint in the continuum
but
exhibit a very strong emission line, beyond what is expected from normal
stellar
populations. It has been believed
that the large equivalent widths
seen
in high-redshift galaxies are intrinsic, and are caused by hot stellar
photospheres
from ongoing star formation. This
would indicate that these
objects
are young, with a primitive composition.
It would also indicate that
they
could be a significant source of reionization photons.
However, there is
an
alternative scenario for the cause of this large Lyman alpha EW. If the
interstellar
medium inside one of these galaxies consisted of clumpy dust
clouds
in a tenuous ionized medium, then continuum photons would penetrate
deep
into these clouds, while the Lyman alpha photons would be resonantly
scattered
at the surface. This would result
in a much higher escape fraction
for
Lyman alpha photons than for continuum photons, effectively enhancing
the
equivalent
width. Thus, a galaxy with this
ISM and older stars could be made
to
look like a young, star-forming galaxy on the basis of its Lyman alpha
EW.
We
will use the GOODS CDF-S treasury data set to measure the continuum
colors
of
Lyman alpha galaxies, and thereby distinguish between these scenarios: If
large
equivalent widths are due to hot photospheres, the continuum should be
blue,
while if they are due to dust enhancement, the continuum should be red.
The
GOODS CDF-S dataset has a limiting magnitude that is 2 magnitudes deeper
than
our ground-based broad-band dataset.
This will reduce the errors on the
broad-band
colors by up to 75%. To find Lyman
alpha galaxies in the CDF-S, we
have
narrow-band images which will be used for selection of z ~ 4.5 galaxies.
By
combining our narrow band images with the high quality GOODS data, we
will
be
able to study the cause of the Lyman alpha equivalent width in
individual
galaxies
at high-redshift.
======================================================================
Proposal
Category: AR
Scientific
Category: STAR FORMATION
ID:
11250
Title:
Shedding
Light on Feedback: The
Interaction of YSO Outflows in L1551
PI:
Adam
Frank
PI
Institution:
University
of Rochester
Energetic
outflows are an ubiquitous phenomena associated with young stellar
objects
and are believed to exert a strong effect on their parent molecular
clouds. In most young clusters the density of
newly forming stars implies
that
parsec scale outflows may sweep over a significant fraction of the
cluster
volume and interact with each other. The nature and dynamics of these
interactions
in an environmental context has yet to be investigated in detail.
Thus
the time is ripe to push forward the construction of detailed ecological
studies
of star formation where the cloud, stars and outflows are seen as a
coherent
interacting system. Such a
perspective is however hampered by the
complexity
of the problem. Proceeding forward will require isolation of key
components
of an overarching theory. Finding relatively clean examples of
outflow
feedback is critical to exploring more general issues star formation
ecology. We seek to carry forward a well focused
study of outflow feedback in
the
L1551 region. Using Adaptive Mesh
Refinement MHD code we propose a
computational
study of multiple jets interacting with their environment and
their
role in altering the properties of their parent cloud.
The questions to
be
addressed are: What is the
combined effect of jets oriented at different
angles
on the overall turbulent motions in the cloud; How effective is the
coupling
between outflows atndcloud material; How effective are the combined
outflows
at disrupting and dispersing the cloud material; How effective are
the
combined outflows at seeding turbulence into the cloud.
======================================================================
Proposal
Category: AR
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11251
Title:
Beyond
the Textbook:
Temporal Systematics of Planetary Nebula Evolution
PI:
Adam
Frank
PI
Institution:
University
of Rochester
The
study of PN shapes has been propelled forward by the high angular
resolution
of HST into a state of flux. Currently the field is undergoing a
profound
reassessment as mechanisms such as binary companions, accretion
disks,
MHD outflow launching and jets become central to a fundamental
understanding
of these objects. Making progress
now requires more systematic
studies
of PN databases (such as HST) which show strong evidence that nebular
shapes
change dramatically in time. In order to connect PN shapes to
evolutionary
mechanisms we propose using high resolution Adaptive Mesh
Refinement
MHD codes, built by the PI, to follow the evolution of three broad
classes
of models and compare their predictions with the existing data,
particularly
a new catalogue of HST PN images.
======================================================================
Proposal
Category: AR
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11252
Title:
Ultraluminous
X-ray sources in elliptical galaxies and the X-ray binary/globular
cluster
connection
PI:
Elena
Gallo
PI
Institution:
University
of California - Santa Barbara
We
propose to exploit archival HST/ACS observations of 100 spheroidal
galaxies
in
the Virgo cluster in order to identify the optical counterparts of about
4500
bright X-ray binaries from our ongoing Chandra survey.
Based on the
shape
of the cumulative luminosity function scaled to the mass of the whole
sample,
we expect to detect around 100 Ultraluminous X-ray Sources (ULXs): the
combination
of the high resolution and sensitivity of the ACS images will
effectively
allow us, for the first time, to discriminate between background
sources
and genuine ULXs for each and every candidate. This, in turn, will
allow
us to determine whether early-type galaxies harbor ULXs in abundance,
and,
if so, whether they are preferably in globular clusters, also readily
identifiable
from the HST images. In addition, this unprecedented catalog of
optical
counterparts of X-ray sources will yield new information on the
properties
of low mass X-ray binaries and their association with globular
clusters.
Finally, by producing a large and clean sample, our study will
settle
the debate on the presence of a break in the X-ray luminosity function
of
this population.
======================================================================
Proposal
Category: AR
Scientific
Category: COSMOLOGY
ID:
11253
Title:
Sizes
and Morphology of z=3.1 Lyman Alpha Emitting Galaxies in the Extended
CDF-S
PI:
Eric
Gawiser
PI
Institution:
Rutgers
the State University of New Jersey
Lyman
Alpha Emitting galaxies (LAEs) seen at high redshift appear to be
galaxies
in the act of formation. They are
currently the most promising
candidates
for the progenitors of typical spiral galaxies like the Milky Way.
The
LAEs tend to be younger, lower in mass, and less chemically evolved than
the
better-studied Lyman Break Galaxies (LBGs). Wide-field
ACS imaging allows
us
to study the physical properties of these objects at kpc scales to gain
a
better
understanding of the interconnected processes of mergers and star
formation
that play fundamental roles in galaxy formation.
We will use
archival
ACS images of the Extended Chandra Deep Field-South from GEMS, GOODS,
and
UDF to study the size and morphology of our sample of 162 Lyman Alpha
Emitters
at z=3.1, 47 of which have confirmed spectroscopic redshifts. We
will
perform the identical analysis on a sample of 34 spectroscopically
confirmed
Lyman Break Galaxies at 2.7<z<3.9 to compare the physical
properties
of
these two families of high-redshift galaxies. At this redshift, the ACS
F606W
and F850LP bands trace the rest-frame ultraviolet radiation from ongoing
star
formation. We will
determine parametric measures of morphology (Sersic
radii,
CAS parameters, Gini coefficient, M20) along with non-parametric
measures
(half-light radii, number of star-forming clumps, size and separation
of
clumps) to provide critical constraints upon models of galaxy formation.
We
will use the objects that lie in the deeper GOODS and UDF regions to
model
uncertainties
in the GEMS results. We will
correct the astrometric zeropoints
of
the GEMS images and reproject them to match the standard GOODS/MUSYC
pixelization
scheme for this field and will offer these images to the
community
via the HST archive.
======================================================================
Proposal
Category: AR
Scientific
Category: COOL STARS
ID:
11254
Title:
Analysis
of Red Giant Oscillations from a 27 Day ACS/WFC Time-Series on NGC 6397
PI:
Ronald
Gilliland
PI
Institution:
Space
Telescope Science Institute
Observations
of solar-like oscillations have started to provide excellent
results
with firm detections in recent years for dwarfs, subgiants and red
giant
stars -- all with radial velocities.
We are now poised to further
exploit
these recent successes with more systematic exploration of
oscillations
in stars across the color-magnitude
diagram (CMD). Giants
are
of
particular interest as allowing tests of stellar structure and
evolution in
this
complicated time in a stars life, while presenting observational signals
of
much larger amplitude than for dwarfs.
Study of stellar oscillations
requires
unusual combinations of long time coverage to obtain
the requisite
frequency
resolution, and precision to detect the fraction of a mmag amplitude
modes
to be studied here. Time coverage
of one week is a lower limit for
study
of modes which in the giants will have periods of 0.25-3 days, while
intensive
observations over multiple weeks would be ideal. We
will show
excellent
success at detecting oscillations in giants (all of which are
strongly
saturated in these data) from a 7 day observation program (GO 9750)
conducted
for extrasolar planet detection in the galactic bulge.
This
proposal
is for analysis of giants serendipitously observed as part of GO-
10424
a 126 orbit program with ACS/WFC on NGC 6397 to probe the bottom of the
white
dwarf cooling sequence. These ~400 exposures over 27 days for NGC 6397
will
allow asteroseismic results on ~40 giants, including mode lifetime
estimates
not possible at only 7 days.
======================================================================
Proposal
Category: AR
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11255
Title:
Simulating
the Evolution of the Galaxy Luminosity Function from z=6 to the Present.
PI:
Fabio
Governato
PI
Institution:
University
of Washington
Using
hydrodynamical simulations of galaxy formation we will provide (1)
updated
predictions for the luminosity function of galaxies in HST and Spitzer
bands
from z ~ 6 to the present and (2) study the physical mechanism that
drives
its evolution. Particular emphasis
will be on providing results easily
comparable
with the real observations: Using
the code Sunrise (developed by
P.Jonsson,
UCSC) we will produce artificial images at kpc resolution for
thousand
of galaxies to obtain individual magnitudes and light profiles in HST
and
Spitzer bands that keep into account the detailed geometry of each
galaxy
and
a self consistent treatment of dust reprocessing of light sources. The
simulations
will consists of a large, 800 million particles SPH simulation of
a
50 Mpc cosmological volume and of several very high resolution
simulations
of
individual galaxies in a cosmological context. While the large volume
will
provide
us with a large statistical sample, the high resolution simulations
will
allow us to identify the physical mechanisms (cold flows, energy
feedback,
mergers) that drive the evolution of the galaxy Luminosity Function
at
different masses and cosmic times.
This double approach will allow us to
properly
evaluate any numerical effects present in the simulations.
======================================================================
Proposal
Category: AR
Scientific
Category: HOT STARS
ID:
11256
Title:
Neon
Abundance in Hot Central Stars of Planetary Nebulae: A New Clue to Late
Stellar
Evolution
PI:
James
Herald
PI
Institution:
The
Johns Hopkins University
We
propose to analyze archival HST spectra of a selected sample of central
stars
of planetary nebulae (CSPN) for which FUSE spectra are also available.
The
primary goal is to derive the neon abundance in their stellar
atmospheres.
While
the abundances of most "hydrogen-rich" CSPN are well explained by
evolutionary
models, those of "hydrogen-deficient" CSPN are not.
One
explanation
for the abundances of the latter is the "born-again" scenario,
which
predicts enhancements in carbon, oxygen, and neon resulting from a late
helium
shell flash. From recent modeling
of far-UV and UV spectra with a
revised
version of the stellar atmosphere code CMFGEN which included high-
ionization
stages of neon, we discovered that in very hot (Teff > 80,000 K)
CSPN,
several transitions from high ionized neon may be visible at UV and far-
UV
wavelengths (Herald, Bianchi & Hillier, 2005).
Our modeling shows that
these
features are highly sensitive to
the neon abundance. We will model
archival
HST spectra concurrently with FUSE spectra to determine the stellar
parameters
such as effective temperature, and also the neon abundance. Our
sample
of hot CSPN spans a range of evolutionary phases. The
neon abundance
is
an important clue to the chemical processing and subsequent dredge-up
and
mixing
in the stellar atmosphere as predicted by the born-again scenario.
Also,
neon is a key component to understanding how CSPN contribute to the
chemical
enrichment of the surrounding ISM.
This study will probe the late
stages
of stellar evolution with unprecedented diagnostics.
======================================================================
Proposal
Category: AR
Scientific
Category: COSMOLOGY
ID:
11257
Title:
Dust
lanes since z~1
PI:
Benne
Holwerda
PI
Institution:
Space
Telescope Science Institute
Dust
lanes are an iconic part of edge-on spirals which predominantly occur in
the
larger faster-rotating disks (V > 120 km/s). This observational fact
has
now
been well established and linked to the vertical gravitational stability
of
spiral disks:
the
ISM in the massive disks collapses into the thin lanes.
A
survey of distant (z<1) edge-on spirals in the Extended Groth Strip
will
give
the corresponding critical velocity at which dust lanes appear and the
fraction
of spirals that display them. This will allow us to study the
evolution
in dust disks with redshift. This
survey will have implications for
the
number of massive HI-rich disks, the balance between ISM and SFR in
earlier
disks and the Tully-Fisher relation.
======================================================================
Proposal
Category: AR
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11258
Title:
Removing
the herring-bone pattern-noise from *all* STIS Side-2 CCD data: a
factor ~3 enhancement in sensitivity
PI:
Rolf
Jansen
PI
Institution:
Arizona
State University
When
STIS resumed operations in July 2001 using the redundant "Side-2"
electronics,
the read-noise of the CCD detector appeared to have increased by
~1
e- due to a superimposed and highly variable "herring-bone"
pattern-noise.
For
the majority of programs aiming to detect signals near the STIS design
limits,
the impact of this noise is far more serious than implied by a mere 1
e-
increase in the amplitude of the read-noise, as it is of a systematic
nature. We have perfected a
method to cleanly remove this pattern-noise
from
raw STIS CCD frames. It is robust, but too costly in terms of CPU time
and
overhead to incorporate into the regular HST/STIS OTFR-pipeline.
Systematic
application therefore demands a one-time dedicated off-line effort
beyond
the scope of the work outlined in the STIS close-out calibration plan.
As
a service to the STIS user community, we propose to fully remove this
excess
noise from *all* raw, un-binned, "Side-2" STIS/CCD frames, and so
significantly
augment the potential of the STIS data base for future NUV--NIR
archival
research. The noise characteristics and effective sensitivity of the
resulting
cleaned data, to be delivered back to the HST Archive, will closely
match
those of CCD data taken during operations with the primary electronics -
--
representing a gain of a factor ~3 in sensitivity at faint flux levels,
at
low
surface-brightness levels, as well as at small spatial scales. All
software
will be documented and made available to the community.
This
archival
calibration legacy program requests a modest, but necessary,
investment
of resources to assure a long-lasting STIS legacy. Science programs
that
will benefit include: (1)
*all* STIS/CCD spectroscopy of faint point- or
extended
sources; (2) *all* STIS/CCD imaging of faint point sources or low
surface-brightness
extended sources; and (3) *all* STIS/CCD programs that
combine
data obtained with both primary and redundant electronics.
======================================================================
Proposal
Category: AR
Scientific
Category: SOLAR SYSTEM
ID:
11259
Title:
Comprehensive
Analysis of Neptune's Features
PI:
Erich
Karkoschka
PI
Institution:
University
of Arizona
Hubble
took an amazing data set of Neptune in nine GO programs between 1994
and
2006, consisting of 408 WFPC2 exposures with several filters present in
each
program. The PIs of these
programs, Hammel, Sromovsky, and Rages,
published
a variety of results about Neptune's atmosphere based on each
program. However, the typical size of the grants
for each program did not
allow
all scientific questions of these rich data sets to be addressed. I
propose
to analyze these 400 images to create a consistent data set spanning
12
years, and I will make even the intermediate results available, such as
400
consistently
calibrated images. The combined
data set will then be able to
address
more far reaching questions than could be done by single data sets.
Whereas
previous studies focused on only a few center-to-limb measurements for
a
limited selection of latitudes and wavelengths, I will investigate the
whole
data
set and analyze 16,000 center-to-limb curves. I
will use the principal
component
analysis and various statistical tests to find the hidden variations
on
Neptune. I created software for a
similar project on Hubble's Saturn
images. I am ready to adapt and apply it to
Hubble's Neptune images. The huge
number
of variable features on Neptune contain an ideal probe about
atmospheric
dynamics. Previous investigations
have only scratched pieces of
the
surface of this treasure. It is
time for a comprehensive study of the
whole
data to discover fundamenatal insights about atmospheric dynamics.
======================================================================
Proposal
Category: AR
Scientific
Category: COSMOLOGY
ID:
11260
Title:
Galaxy
Shapes and Gravitational Lensing
PI:
Charles
Keeton
PI
Institution:
Rutgers
the State University of New Jersey
The
mass distributions in gravitational lens galaxies--even just the stellar
components--are
almost certainly more complicated that we usually assume.
This
probably contributes to the problems with lensing constraints on the
Hubble
constant. It might also confound
studies of dark matter substructure:
we
recently found that edge-on disk components in elliptical lens galaxies
can
create
"anomalous" flux ratios similar to those often attributed to dark
matter
substructure. We propose to
critically examine how galaxy shapes
affect
these applications of gravitational lensing. We
will use real galaxies
from
the GEMS (Galaxy Evolution from Morphology and SEDs) survey to construct
a
large catalog of mock lenses.
Working with mock lenses allows us to perform
controlled
experiments; but the power comes from using real galaxies so that
we
automatically include structures that are more general than conventional
parametric
lens models yet are guaranteed to be realistic. We
will use the
catalog
of mock lenses to determine whether the observed incidence of
anomalous
flux ratios can be explained by "disky" lens galaxies or requires
dark
matter substructure. In doing so, we
will derive new constraints on the
amount
of dark matter substructure required or allowed by gravitational
lensing,
which realistically account for the complexity in galaxy (stellar)
mass
distributions. We will also use
the mock lenses to provide the first
objective
calibration of non-parametric lens models.
======================================================================
Proposal
Category: AR
Scientific
Category: ISM IN EXTERNAL GALAXIES
ID:
11261
Title:
Dynamically-Driven
Star Formation in M51
PI:
Jin
Koda
PI
Institution:
California
Institute of Technology
We
propose to investigate gas dynamical environments around star forming
regions
in the ground-design spiral galaxy M51. The archival HST/ACS Halpha
image
will reveal the location and properties (e.g. size, luminosity) of HII
regions.
The CARMA key project observes molecular gas over the entire M51
disk,
overlaying the gas density and velocity structures on the HII image.
CARMA
has sufficient spatial and velocity resolutions for revealing dynamical
environments
(e.g. shocks, shears) around individual star forming regions. We
will
correlate the HII region properties with their dynamical environments.
The
comparison of CARMA and HST image will reveal the previously unseen
connection
between galactic gas dynamics and the trigger of star formation.
======================================================================
Proposal
Category: AR
Scientific
Category: COSMOLOGY
ID:
11262
Title:
Deepening
the Hubble UDF - Constraining the High-z Galaxy Luminosity Function
Faint End
Slope and Reionization
PI:
Anton
Koekemoer
PI
Institution:
Space
Telescope Science Institute
We
propose to significantly improve the depth of the Hubble Ultra Deep
Field
(UDF)
by ~0.4-0.5 magnitudes (equivalent to doubling the exposure time of the
original
UDF), through recalibrating and reprocessing the original UDF ACS
data
with improved reference files and new techniques to remove a variety of
electronic
instrumental signatures from the images. Since ACS has now been in
operation
for almost 5 years, this provides an opportunity to improve
significantly
upon the original calibration which had been performed using the
best
available information 18 months after the installation of ACS. Our team
has
the demonstrated expertise to carry out this recalibration and
reprocessing,
and we also have the demonstrated ability to release such
products
to the commmunity on a timely basis. We propose this as an Archival
Legacy
program because the resulting dataset, as well as the techniques that
we
are using, will be of great value to the community and should enable
significant
new science to be obtained from this unique dataset. In addition,
the
resulting improvements on the number counts of redshift ~6 dropout
sources
will
significantly improve the current uncertainties in this field regarding
the
faint end slope and normalization of the luminosity function of the
redshift
~6 population, and ultimately the role played by these sources in
reionizing
the universe.
======================================================================
Proposal
Category: AR
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11263
Title:
Modeling
Coronagraphic Images of Beta Pictoris and other Debris Disks with Gas
PI:
Marc
Kuchner
PI
Institution:
NASA
Goddard Space Flight Center
We
propose to study the dynamics of dust grains in the Beta Pictoris disk
and
to
model the X pattern, otherwise known as the "warp," revealed in ACS
Coronagraph
images. We will use our models to
test the idea that the X
pattern
does not stem from the gravitational perturbations of a planet and we
will
tie together what we know about the dust and what we know about the gas
in
this nascent planetary system. We
will provide numerical tools to the
astronomical
community that they can use to model other new and upcoming HST
images
of debris disks with gas.
======================================================================
Proposal
Category: AR
Scientific
Category: UNRESOLVED STELLAR POPULATIONS
ID:
11264
Title:
Blue
Tilts and Other Properties of Halo Globular Clusters in Nearby Galaxies
-
Cosmological or Observational Bias?
PI:
Arunav
Kundu
PI
Institution:
Michigan
State University
Old
metal-poor globular clusters are seen in large numbers in the halos of
all
nearby
galaxies. Cosmological simulations suggest that these clusters, which
appear
as the blue peak in the typical bimodal color distribution of globular
cluster
systems, are among the first objects to form at high redshift. Until
recently
these primordial clusters were assumed to be `universal' because the
properties
of blue globular clusters found in all types and sizes of galaxies
appeared
to be identical. A series of new ACS-based studies, using the ACS
Virgo
Cluster Survey (GO-9401) data and other samples (GO-9427, GO/DD-9714),
suggest
that there is a mass-metallicity relation in the blue halo globular
clusters.
The brighter blue clusters trend to redder colors in this `blue-
tilt'
phenomenon. This seems to suggest that larger globular clusters have
self
enriched either because they were formed in large gas clouds, or because
in
the past they had significant dark matter halos that have subsequently
been
stripped.
These ACS studies also find that the mean metallicity of the halo
clusters
increases with the mean mass of the host galaxy. It has been argued
that
this is evidence of self enrichment in large halos and points towards an
in
situ model of galaxy formation. We suggest that both these correlations
are
caused
by subtle systematic observational effects that have been overlooked in
previous
studies. We propose to undertake a systematic analysis of the
globular
cluster systems of the 145 galaxies observed by the ACS Virgo and
Fornax
cluster surveys (GO-9401, GO-10217), and the mosaic of M104 (GO/DD-
9714)
in order to answer the crucial question, `Just how universal are the
properties
of the metal-poor halo globular clusters?'. These ACS observations
are
likely to remain the largest globular cluster datasets for the
foreseeable
future.
Our independent analysis of these extended datasets will provide an
important
check on the results found for globular cluster systems and their
implications
on galaxy formation and evolution.
======================================================================
Proposal
Category: AR
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11265
Title:
Highly
Ionized Plasma in the Milky Way:
A
Benchmark for Feedback Studies in the Universe
PI:
Nicolas
Lehner
PI
Institution:
University
of Notre Dame
We
propose to produce an homogeneous study of the high-resolution STIS
E140H
(1.5-2.7
km/s resolution) spectra of the interstellar Si IV, C IV, and N V
absorption
along 26 extended Galactic sight lines to study the properties of
highly
ionized gas in the Milky Way.
Absorption from these ñhigh ionsî is
used
to probe hot gas from the Milky Way to high-redshift primordial
galaxies.
However,
only in our own Galaxy have they been observed with high enough
spectral
resolution to fully resolve the line profiles. Such observations have
revealed
surprisingly narrow absorbing clouds that would not have been
identified
at lower resolution and that likely trace non-equilibrium cooling
or
photoionization of feedback-driven gas.
The sight lines chosen for study
in
this work sample a variety of physical environments or structures (e.g.,
the
lower Galactic halo, H I shells and supershells, spiral arm and interarm
gas,
and evolved supernova remnants).
The very high resolution of the
observations
to be analyzed will allow us to derive properties for the
individual
physical clouds connected to such structures and to study effects
unobservable
at lower resolutions where the clouds are smeared together. Our
survey
has three main goals:
1)
to produce an homogeneous reduction and
analysis
of the archival E140H spectra of these stars; 2) to determine the
primary
ionization mechanisms responsible for the highly ionized gas in
various
physical environments in the Milky Way; 3) to understand the physical
origins
of the different types of highly-ionized gas so that the signatures
seen
in the Milky Way might be used for understanding highly ionized gas in
the
halos of neighboring galaxies, in starburst outflows, and in primordial
galaxies.
======================================================================
Proposal
Category: AR
Scientific
Category: STAR FORMATION
ID:
11266
Title:
Radiation-induced
Grain Dynamics in Dust Disks:
Radiation
Pressure, Poynting-Robertson Drag, and Photophoresis
PI:
Aigen
Li
PI
Institution:
University
of Missouri - Columbia
We
propose a theoretical program to rigorously calculate the radiation
pressure
and Poynting-Robertson drag parameters for both porous and compact
grains
in dust disks illuminated by stars of a wide range of spectral types,
using
the scattering parameters obtained from our HST Cycle 15 theory project.
We
also propose to study the rotational excitation of grains in gas-rich,
optically
thin disks (through collisions with neutrals, ions, "plasma drag"
which
may drive them to rotate suprathermally) to test the "photophoresis"
hypothesis
which was recently invoked to explain the central clearing and the
formation
of narrow rings in dust disks. This program will create a web-based
library
of radiation pressure and Poynting-Robertson drag parameters for both
porous
dust and compact dust (including nano-sized grains) as a function of
size,
composition, porosity (for porous dust), and stellar spectral type. This
library
will be made publicly available via the WWW at
http://www.missouri.edu/~lia/.
These parameters are essential (1) for modeling
disk
dynamics to interpret the un-smooth structures (e.g. asymmetry, warps,
inner
holes, clumps, rings) seen in scattered light images of disks obtained
with
HST, and (2) for reliably determining the dust removal and replenishment
rates
of debris disks as well as disk evolution.
======================================================================
Proposal
Category: AR
Scientific
Category: STAR FORMATION
ID:
11267
Title:
Dynamical
Heat Re-Distribution Modeling in Hot-Juipter's
PI:
Douglas
Lin
PI
Institution:
University
of California - Santa Cruz
Observations
of transiting hot-Jupiter's have opened a new avenue for
exploring
the structure and atmospheres of giant extra-solar planets.
Significantly
different then our own giant planets, tidally locked hot-
Jupiter's
are subject to intense irradiation from their host star, which
drives
supersonic winds across the face. In this proposal we describe a study
coupling
full 3-dimensional radiative hydrodynamic models to radiative
transfer
models and detailed opacity studies. Noticeably absent in current
studies,
these models will allow us to self-consistently explore existing
observations
and predict properties of new objects, including spectral
signatures
and light curves. These predications should be directly testable by
the
Hubble Space Telescope and should lead to a greatly improved
understanding
of
atmospheric physics on the surface of extra-solar planets.
======================================================================
Proposal
Category: AR
Scientific
Category: QUASAR ABSORPTION LINES AND IGM
ID:
11268
Title:
New
Synthesis Models of the Extragalactic Ionizing Background
PI:
Piero
Madau
PI
Institution:
University
of California - Santa Cruz
The
intergalactic medium (IGM) contains evidence of the epochs of galaxy
formation,
metal enrichment, reionization, and reheating of the baryons left
over
from the Big Bang. Hydrogen, helium, and many heavy elements (C, Si, N,
0)
observed by Hubble through quasar absorption line studies are kept
highly
ionized
by the extragalactic UV/soft X-ray background (UVB) from active nuclei
and
star-forming galaxies. The spectrum and intensity of the UVB is one of
the
most
uncertain yet critically important astrophysical input parameters into
cosmological
simulations of the IGM. It provides the ionization corrections
needed
for interpreting QSO absorption-line data and derive crucial
information
on the distribution of primordial baryons and of the
nucleosynthetic
products of star formation. We propose here to build improved
synthesis
models of the UVB intensity, spectrum, and evolution with redshift
using
the radiative transfer code CUBA, updating and extending our previous
results
(Haardt & Madau 1996). We will adopt up-to-date determinations of
the
quasar
optical/X-ray luminosity functions and intrinsic spectra, intergalactic
photoelectric
absorption, and cosmic star formation history from GOODS/ACS
data.
This research will make use, enhance the value of and have a lasting
benefit
for past and observational programs with the HST. We will make the
latest
version of CUBA freely available for public use, allowing for several
user-supplied
quantities such as source emissivity
as a function of frequency
and
redshift, and amount of intervening absorption.
======================================================================
Proposal
Category: AR
Scientific
Category: HOT STARS
ID:
11269
Title:
Determining
O star mass loss rates from Sulfur wind lines.
PI:
Derck
Massa
PI
Institution:
SGT,
Inc.
The
winds of massive stars power and enrich the ISM, control the evolution
of
the
stars, determine their ultimate fate and the nature of their remnants,
determine
the appearance of HRDs in young, massive clusters and star-bursts,
and
play a major role in the initial stages of massive star cluster
formation
and
evolution. Thus, recent
suggestions that O star mass loss rates are up to
ten
times less than previous observational determinations or theoretical
expectations
warrant further investigation. Perhaps
the most compelling
evidence
for reduced mass loss rates comes from analyses of the far UV P V
1118,
1128A resonance doublet, which has become widely accessible since the
launch
of FUSE. Because Phosphorus has a
low cosmic abundance, this doublet
never
saturates, providing accurate estimates of the mass loss rate times the
ionization
fraction. By examining the
strength of this doublet as a function
of
temperature for a large sample of stars, it is argued that the ion
fraction
of
P V must be near unity somewhere in the O star range.
If this conjecture
is
correct, then the mass loss rates inferred from P V never exceed 10-15%
of
previous
expectations. In this
proposal, we intend to verify this important
result
by analyzing HST and FUSE data for the wind lines of three adjoining
stages
of Sulfur (S IV, V and VI) in a sample of LMC O stars. We show how the
analysis
of these lines can furnish a direct measurement of the mass loss rate
from
UV wind lines alone, without the need to assume an ion fraction. As a
result,
they provide a powerful verification of the P V results.
Furthermore,
we
argue that our results should not be strongly affected by clumping in
the
winds,
a mechanism often invoked to explain the differences between different
observational
measures of mass loss rates.
======================================================================
Proposal
Category: AR
Scientific
Category: HOT STARS
ID:
11270
Title:
The
Effective Temperatures and Physical Properties of O- type Stars at Low
Metallicity
PI:
Philip
Massey
PI
Institution:
Lowell
Observatory
An
accurate knowledge of the effective temperatures of O-type stars is the
key
to
knowing their other physical properties.
Improvements in stellar
atmosphere
models in the past few years have significantly reduced the deduced
temperatures
of Galactic O-type stars due to the effects of wind- and line-
blanketing. At the lower metallicities of the SMC
and LMC, blanketing should
have
a lesser effect, but there is considerable disagreement in the
literature
at
present as to the effective temperatures scale for SMC and LMC O stars. We
plan
a comprehensive study using HST archive UV data supplemented by optical
ground-based
data recently obtained with the Magellan 6.5-m telescope.
In
addition
to using improved data, our study will apply different models
(FASTWIND
and CMFGEN) to the same data-sets, and we will also separately and
jointly
determine physical parameters based upon the UV and optical spectra.
This
will lead to a much better understanding of where the
any systematic
differences
originate. In the end, we expect
to have not only a definitive
effective
temperature scale of low-metallicity O-type stars, but also a very
realistic
estimate of what the uncertainties are in that scale.
This study
will
also serve as the impetus for long-term improvement in the stellar
atmosphere
models of hot luminous stars.
======================================================================
Proposal
Category: AR
Scientific
Category: HOT STARS
ID:
11271
Title:
Establishing
a Zero Motion Reference Frame for the FGS
PI:
Bernard
McNamara
PI
Institution:
New
Mexico State University
We
propose to measure the internal proper motions of the stars in M35 that
are
used
to calibrate the HST/FGS. The goal of this effort is to remove the
influence
these stars have the FGS distortion map. Employing the approximately
108
orbits of available archival FGS data, these motions can be determined
to
an
accuracy of 0.05 mas/year. By iteratively measuring these motions using
successively
longer time bases and then accounting for them in the distortion
map,
their influence on this map can be essentially eliminated.
======================================================================
Proposal
Category: AR
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11272
Title:
An
Archival Study of Solar-System-Scale Interstellar Structure
PI:
David
Meyer
PI
Institution:
Northwestern
University
The
evidence for significant solar-system-scale (< 100 AU) structure in
the
diffuse
ISM has increased dramatically over the past decade through multi-
epoch
H I 21 cm and optical Na I absorption-line observations of various
extragalactic,
pulsar, and stellar sightlines.
Possible explanations for this
structure
range from small-scale filamentary geometries to fractal geometries
driven
by turbulence to a separate population of small, dense self-gravitating
clouds. The latest Na I data now indicate that
the solar-system-scale Na I
structure
is most common in the vicinity of dynamic interstellar regions.
However,
the physical interpretation of this structure is unclear because Na I
is
not the dominant Na ion in H I clouds.
Such a detailed understanding
requires
the diagnostic power of the rich diversity of interstellar species
observable
in the UV. We have identified 13
objects in the HST data archive
with
multi-epoch STIS echelle observations of UV interstellar absorption
lines. We propose to analyze the interstellar
lines in the 212 datasets
comprising
these observations and probe the physical character of any temporal
profile
variations. Our specific goals in
this archival study are to assess
the
extent of solar-system-scale structure in the H I gas as well as the
thermal
gas pressure, electron density, and dust content of any observed
structure.
======================================================================
Proposal
Category: AR
Scientific
Category: HOT STARS
ID:
11273
Title:
Tracing
the wind interface of the massive binary Eta Carinae
PI:
Krister
Nielsen
PI
Institution:
Catholic
University of America
The
binarity of Eta Carinae has been debated for a long time, but most
recent
evidence
favors a binary star interpretation. However, very little is known
about
the nature of the companion star. Over Eta Carinae's spectroscopic
period
many observable wind lines in the NUV/Optical region, have been shown
to
exhibit peculiar line profiles with unusual velocity shifts relative to
the
system
velocity. Some of the lines are exclusively blue-shifted over the
entire
5.54 yr cycle and their
ionization/excitation imply formation in the
interface
between the two massive stars. Especially, the He I emission lines
are
mainly formed in the wind interface region. Since the wind momentum is
much
larger for the primary star than its companion, the wind interface is
located
fairly close to the companion. Consequently, by tracing the He I
emission
we can construct a radial velocity curve that will describe the
motion
of the companion star and will derive the relation between the masses
of
the binary system stars. Furthermore, we will measure velocity and
intensity
variations in H I and Fe II to further investigate the
ionization/excitation
structure throughout Eta Carinae's wind. The analysis of
the
central source of Eta Carinae, due to the closeness of the two stars in
the
binary system (30 AU) and the intervening matter in line-of-sight
towards
Eta
Carinae, is extremely dependent on data obtained with high angular
resolving
power. The HST archival data is crucial for the continuance of this
project.
======================================================================
Proposal
Category: AR
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11274
Title:
A
Final Calibration of the Primary WFPC2 Emission-Line Filters Using the
Orion
Nebula
PI:
C.
O'Dell
PI
Institution:
Vanderbilt
University
Emission-line
imaging with the WFPC2 has been dominated by use of the F656N, F
658N,
and F502N filters.These filters require on-orbit calibration in order to
convert
their signals to absolute energy surface brightness units. This has
previously
been done, but there is a question of time variation of their
properties
and this will be addressed by special observations of the Orion
Nebula
as part of calibration program 11038. This archive program will use the
previously
adopted method that uses a well-calibrated long-slit reference
sample
to calibrate the data. There is also a mid-lifetime set that will allow
tracking
variations with time. I will also determine if a new set of multi-
aperture
groundbased data is satisfactory for use as a reference source and if
it
is, to determine variations in the calibration constants across the
individual
CCD detectors and with better time resolution by using five
additional
studies.
======================================================================
Proposal
Category: AR
Scientific
Category: HOT STARS
ID:
11275
Title:
The
Effect of Metallicity on the Rotation Rates of Massive Stars
PI:
Laura
Penny
PI
Institution:
College
of Charleston
Stellar
interior models are critical tools used in all branches of astronomy
from
chemical evolution and population synthesis studies to the determination
of
evolutionary masses. Until recently the effects of rotation were not
included
in these codes. The new models show that rotation induces interior
mixing
that produces some drastic external changes for massive stars while
they
are still core-hydrogen burning. While the inclusion of rotation was
expected
to explain the enhanced surface abundances seen in some stars, the
prediction
that massive stars have luminosities that are rotation dependent
was
not expected. This last prediction creates a serious scatter in the
mass-
luminosity
relationship and makes the determination of an evolutionary mass
essentially
impossible. These new models must be tested to determine if their
treatment
of angular momentum is correct. A straightforward method is to
determine
if massive starsÍ rotation rates match those predicted by the new
models.
At solar or Galactic metallicity (Z = 0.020), massive stars are
expected
to quickly slow their rotation speeds while on the main sequence
(MS).
Stars at lower metallicity (Z) experience reduced mass loss rates and
subsequently
retain more of their angular momentum during the MS. The HST
archive
at the Multimission Archive at Space Telescope (MAST) contains spectra
of
180 LMC (Z = 0.007) and SMC (Z = 0.004) O-type stars.
This is an extremely
large
sample of O-type spectra, all observed with the same instrument. It
contains
both cluster and field stars. These stars represent a completely
uniform,
unbiased sample for evaluating the predictions from the new stellar
interior
models. Projected rotation velocities for all stars will be obtained
through
a cross-correlation methodology that we have used successfully in the
past
with both IUE and HST/STIS spectra. Comparisons of the rotation rates of
unevolved
(close to ZAMS) stars at low Z to those of the same classes at
higher
Z will determine if the initial rotation rates of massive stars are
metallicity
dependent. Comparisons of the rotation rates of evolved (close to
TAMS)
massive stars to the unevolved stars in the same metallicity environment
will
determine the extent of angular momentum (and hence mass) loss during
the
core
hydrogen burning. The proposed survey represents a critical and needed
test
of the treatment of angular momentum in the new stellar models and the
accuracy
of the models predictions.
======================================================================
Proposal
Category: AR
Scientific
Category: AGN/QUASARS
ID:
11276
Title:
Hydrodynamical
models of Narrow Line Regions in Seyfert Galaxies
PI:
Daniel
Proga
PI
Institution:
University
of Nevada - Las Vegas
We
propose to study large-scale outflows from Seyfert galaxies (SG). We
will
explore
our hydrodynamical model of flows influenced by the gravitational and
radiation
fields of the central part of SG. The model predicts an outflow in
the
polar region which is driven by thermal and radiation pressures and is
confined
by a very hot ambient gas accreting on to a central black hole. Our
preliminary
calculation shows that this model promises to explain the
kinematics
of winds in the Narrow Line Regions of SG. We
will apply the model
to NGC 1068, NGC 4151, and Mrk 3 where
winds were spatially resolved by
HST.
In
particular, we will compute, based on our
wind model, synthetic images and
position-dependent
line profiles (i.e., for many
positions along a given
slit)
for direct comparison with the
data from the Space Telescope Imaging
Spectrograph. A similar model can be apply to
outflows from other Active
Galactic
Nuclei and accreting systems.
======================================================================
Proposal
Category: AR
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11277
Title:
RR
Lyrae Variables in Local Group Galaxies
PI:
Ata
Sarajedini
PI
Institution:
University
of Florida
We
propose to reduce and analyze WFPC2 images of 5 Local Group galaxies in
order
to identify and characterize their RR Lyrae variables. These galaxies,
which
include NGC 147, IC 10, LGS 3, Tucana,
and Andromeda V, have no
published
variability studies using HST imaging.The presence of RR Lyrae
variables
would suggest that an old (Age >~ 10 Gyr) stellar population is
present
in these galaxies. In additon,
because the minimum-light color of ab-
type
RR Lyraes is a constant irrespective of metallicity or period, these
stars
can be used to study the extinction properties of each galaxy.
Furthermore,
the period of ab-type RR Lyraes is
directly related to their
metal
abundance so that we can also study the
metallicity distribution
function
of each galaxy. Lastly, it is well known that RR Lyraes are excellent
distance
indicators allowing us to measure the distance of each galaxy.
======================================================================
Proposal
Category: AR
Scientific
Category: AGN/QUASARS
ID:
11278
Title:
AGN
Variability in the GOODS Fields
PI:
Vicki
Sarajedini
PI
Institution:
University
of Florida
Variability
is a proven method to identify intrinsically faint active nuclei
in
galaxies found in deep HST surveys.
We propose to extend our short-term
variability
study of the GOODS fields to include the more recent epochs
obtained
via supernovae searchers, increasing the overall time baseline from 6
months
to ~2.5 years. Based on typical
AGN lightcurves, we expect to detect
~70%
more AGN by including these more recent epochs. Variable-detected
AGN
samples
complement current X-ray and mid-IR surveys for AGN by providing
unambigous
evidence of nuclear activity.
Additionallty, a significant number
of variable nuclei are not associated with
X-ray or mid-IR sources and would
thus
go undetected. With the increased
time baseline, we will be able to
construct
the structure function (variability amplitude vs. time) for low-
luminosity
AGN to z~1. The inclusion of the
longer time interval will allow
for
better descrimination among the various models describing the nature of
AGN
variability. The variability
survey will be compared against
spectroscopically
selected AGN from the Team Keck Redshift Survey of the
GOODS-N
and the upcoming Flamingos-II NIR survey of the GOODS-S.
The high-
resolution
ACS images will be used to separate the AGN from the host galaxy
light
and study the morphology, size and environment of the host galaxy.
These
studies will address questions concerning the nature of low-luminosity
AGN
evolution and variability at z~1.
======================================================================
Proposal
Category: AR
Scientific
Category: ISM AND CIRCUMSTELLAR MATTER
ID:
11279
Title:
A
Legacy Archive PSF Library And Circumstellar Environments (LAPLACE)
Investigation
PI:
Glenn
Schneider
PI
Institution:
University
of Arizona
NICMOS
coronagraphy, with well-matched template Point Spread Function (PSF)
subtraction,
probes the closest environments of occulted targets with the
highest
imaging sensitivity in intrinsically high contrast fields at the
smallest
radial distances afforded, uniquely, by HST. NICMOS PSF-subtracted
coronagraphy
has been invoked in a wide variety of HST programs with science
themes
as divergent as detecting and characterizing disks of circumstellar
material
in neo-natal stellar environments, to studying faint nebulosity
associated
with luminous active galaxies, to searching for planetary-mass
companions
in extrasolar planetary systems recently born and in the "stellar
graveyard."
The investment in HST time in the execution of these and other
programs,
which has resulted in more than 8450 NICMOS coronagraphic images to
date,
has met with mixed returns. Stunning (but infrequent) successes,
importantly
advancing their fields highlight much more frequent, unfortunately
common,
failures arising from highly compromised technically-achievable
performance
due to the lack of suitable template PSFs required to produce
high-fidelity,
photometrically robust, high contrast coronagraphic images. We
propose
to remedy this situation by undertaking a rigorous, homogeneous, and
complete
recalibration and analysis of the full archival set of raw NICMOS
coronagraphic
images previously obtained and residing in the MAST to create a
Legacy
library of template PSFs enabling the recovery of the large body of
science
otherwise lost. This PSF library, along with generically applicable
analysis
software that we will deliver to STScI, will:
(1)
critically augment
the
needs of future observational programs reliant on high-fidelity PSF
subtractions,
(2) increase their yields and photometric efficacy, (3) reduce
the
observing time (HST orbit allocations) otherwise required for near-
contemporaneous
reference PSF observations, and (4) greatly enrich the yet-
unrealized
potential of the many NICMOS coronagraphic observations already
acquired
from the broad spectrum of science programs previously executed. We
will
then use the enabling power of the PSF library to re-reduce and re-
analyze
all archival NICMOS coronagraphic observations of circumstellar disk
and
VLM stellar, brown dwarf, and EJP companion candidate stars (~ 400
targets)
to probe for previously undetected circumstellar disks. Through image
analysis
and modeling we will ascertain the physical properties of newly-
discovered
disks and their constituent grains. With a very large and
homogeneously
contrast-limited sample of optimally PSF-subtracted images, we
will
also set spatially resolved dust-scattered light flux density limits
from
non-detections
to constrain the properties of the many IR-excess (and other)
sources
in this sample.
======================================================================
Proposal
Category: AR
Scientific
Category: HOT STARS
ID:
11280
Title:
The
Variable Magnetic White Dwarf in the Hyades Eclipsing Binary V471 Tauri
PI:
Edward
Sion
PI
Institution:
Villanova
University
V471
Tau is a detached eclipsing binary in the Hyades cluster consisting of a
hot
magnetic white dwarf and a rapidly rotating K
dwarf companion. With an
orbital
period of only 12.5 hour, the stellar components emerged from common
envelope
interactions which drastically reduced their initially wide
separations.
It is the prototypical pre-cataclysmic binary. The white dwarf
exhibits
soft X-ray, EUV and optical variations on its 9.25 minutes rotation
period.
These variations are due to heavy elements accreted onto the WD's
magnetic
poles from the companion's wind. The implied accretion rate from the
companion's
wind, however, is so low that a magnetic propeller mechanism must
be
rejecting most of the material that attempts to accrete.
We propose a
comprehensive
analysis of all existing HST STIS echelle spectroscopic
observations
that will focus on: (1)
the variation of line strengths of
accreted
ions in the WD photosphere over the 9.25 minute rotation period of
the
WD, covering the four years over which STIS echelle spectra were taken;
(2)
probe the Zeeman splitting we first detected in a greater mix of
metallic
absorptions
species, thus accurately determining the magnetic field strength
and
its variation at the rotational period; (3) determine the chemical
abundances
of accreted metals and study the process of magnetic accretion
onto,
and diffusion of heavy elements out of, the photosphere of the magnetic
white
dwarf using newly available models and diffusion parameters by Co-I J.
Dupuis;
(4) refine the mass of the WD and other system parameters with a more
complete
radial velocity curve.
======================================================================
Proposal
Category: AR
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11281
Title:
The
Durations of Starbursts in Blue Compact Galaxies
PI:
Evan
Skillman
PI
Institution:
University
of Minnesota - Twin Cities
The
starburst phenomenon is a very important phase of galaxy evolution, and
especially
so for dwarf galaxies. The
duration of the burst is important
because
it impacts both the evolution of the galaxy itself and the evolution
of
the local environment external to the galaxy. In
addition to the physical
conditions
and evolution of the galaxy, the length of the burst and degree of
"burstiness"
affects the detectability of low luminosity galaxies.
There is
no
consensus in the literature on the typical duration of a burst in a
dwarf
galaxy;
some studies favor durations of roughly 5 Myr, and others roughly 100
Myr. We propose to resolve this
discrepancy. The HST archive
contains high
quality
imaging observations of a number of nearby starbursts in dwarf
galaxies
(often called Blue Compact Dwarf galaxies or BCDs).
However, these
have
been obtained through a number of diverse investigations focusing on a
wide
variety of science questions. Here we propose a systematic, uniform
analysis
of these nearby BCDs that will produce star formation histories
(SFHs)
with a primary goal of determining the duration of the burst.
Specifically,
we will:
(1)
reduce the photometry in a uniform manner using
programs
optimized for HST observations, (2) use two of the most sophisticated
programs
available to derive optimal star formation histories from the
resulting
color-magnitude diagrams, including modeling of the effects of
differential
extinction, and (3) compare these results and conduct Monte Carlo
simulations
in order to securely quantify the uncertainties in the derived
star
formation rates. This approach
will allow us, for the first time, to
compare
the results for a significant sample in a uniform and unbiased way,
and
thus, draw unambiguous conclusions regarding the duration of starbursts
in
BCDs.
======================================================================
Proposal
Category: AR
Scientific
Category: SOLAR SYSTEM
ID:
11282
Title:
Diurnal
Martian Ice Cloud and Ozone Maps from HST WFPC2 Multi-Band Images
PI:
Tracy
Smith
PI
Institution:
Space
Science Institute
Mars
atmospheric aerosols such as dust, ice and ozone play important roles in
the
meteorology of the planet. Much
controversy still exists among observers
and
modelers over what represents the average Mars atmosphere, and how it
changes
diurnally, seasonally and interannually.
Ozone is an important tracer
of
the photochemical processes responsible for the stability of Mars'
carbon
dioxide
atmosphere. Water vapor is also an
important trace element in
atmospheric
models, and contributes to the formation of water ice clouds.
Seasonal
global temperature fluctuations affect the water vapor saturation
altitude
(hygropause), which in turn determines water ice cloud formation
altitude at low- to mid-latitudes.
Models predict large diurnal ozone
fluctuations
as a result of the seasonal changes in the hygropause.
The
mapping
of global, diurnal water ice clouds and ozone column densities can
only
be performed by using Hubble Space Telescope (HST) WFPC2 multi-band
images
of Mars. No other spacecraft,
including Mars Global Surveyor and Mars
Express,
can achieve this. Diurnal water
ice cloud and ozone column density
maps
derived from a long baseline of HST measurements (1993-2004), would
serve
as
useful reference data for workers using current mission data, such as
Mars
Orbital
Camera (MOC), providing context and connection to their temporally
limited
data. A water ice map and an ozone
column density map have already
been
produced by the PI from the January 2001 HST cycle9 Mars multi-band
WFPC2
images.
======================================================================
Proposal
Category: AR
Scientific
Category: AGN/QUASARS
ID:
11283
Title:
The
Near and Far Sides of M87
PI:
William
Sparks
PI
Institution:
Space
Telescope Science Institute
We
propose to assemble the deepest ever image of the M87 jet and its
environs
using
archival data acquired for unrelated purposes. By studying the AGN, the
jet
and ISM physics we address the role and nature of AGN feedback to the
ISM
and
the quantitative physical nature of the jet and AGN. With over 50 orbits
of
ACS/WFC F606W and F814W imaging we can detect or place significant upper
limits
on the brightness of a counter-jet, yielding insight into the jet
beaming
factor and orientation to the line of sight. With this deepest ever
jet
image, we will also probe the extent to which optical emission can be
traced
both from the primary jet into the radio lobe and the SE synchrotron
hotspot
at the termination of the counter-jet, to quantify optical synchrotron
loss
processes and map spectral ageing. We will seek scattered light from
ambient
hot electrons known to be present in the nuclear regions of M87 and
hence
identify the allowed parameter space involving nuclear luminosity,
nuclear
beam pattern and ISM density. Electron scattering in particular is
symmetric
with respect to direction and hence we have the best chance to
detect
a scattering beam in the counter-jet direction. Faint dust features and
emission-line
filaments will also be mapped and compared to the radio source
morphology
to better understand their interaction and provide information on
the
energetic interplay between radio sources, jets and the ISM.
======================================================================
Proposal
Category: AR
Scientific
Category: RESOLVED STELLAR POPULATIONS
ID:
11284
Title:
Intermediate
Mass Black Holes in Globular Clusters: Key
Photometric Fingerprints
PI:
Michele
Trenti
PI
Institution:
Space
Telescope Science Institute
Intermediate
Mass Black Holes (IMBHs) are important and interesting objects.
Their
existence has been predicted in different astrophysical contexts, such
as
in runaway collapse of massive stars in Globular Clusters (GCs) and as
remnants
of the explosion of Pop III stars in the early universe. Ultra
Luminous
X-ray sources observed in various environments may be IMBHs, but
their
nature remains poorly understood. GCs may ultimately present the best
chance
of finding IMBHs. HST line-of-sight velocity studies have suggested
IMBHs
in M15 and G1, but these detections are not unambiguous. HST proper
motion studies are now also underway, but
these are challenging and have not
yet
yielded any detections. This proposal therefore addresses an alternative
approach
for finding IMBHs in GCs with HST, namely through their photometric
signature.
Numerical simulations have shown only recently that IMBHs leave a
clear
photometric signature in GCs that differs considerably from the
simplified
analytical predictions that have been accepted for decades. Instead
of
a steep cusp, an IMBH induces a shallow cusp within a large core radius.
Recent
WFPC2-HST archival analysis by Noyola & Gebhardt has shown that many
GCs
have surface brightness profiles that are generically consistent with
this
prediction.
However the data-model comparisons carried out to date have not
been
sophisticated: only projected mass
profiles were derived from N-body
models
and there has been no attempt to simulate real data, taking into
account
star colors, luminosities, PSFs, and crowding. Therefore we propose to
facilitate
credible IMBH detections in GCs based on photometry by:
(a)
running
sophisticated
N-body simulations of star clusters with IMBHs, primordial
binaries
and stellar evolution; and (b) simulating photometric datasets from
these
observations and deriving surface brightness profiles from them using
techniques
similar to those customarily applied to real data. This work is
ideally
suited for the HST Theory program as HST is the only telescope with
sufficient
resolution to measure photometric profiles down to the required
resolution.
Much effort has been invested in such GC observations (e.g., a
134-orbit
Cycle 14 ACS survey - PI Sarajedini), yet theoretical simulations
are
generally not performed as part of such programs. Our work will be
important
for the interpretation of these and other data, and it will
complement
efforts to detect IMBHs in globulars using dynamics or X-ray
observations.
======================================================================
Proposal
Category: AR
Scientific
Category: COSMOLOGY
ID:
11285
Title:
TRGB
Distances from Archived Data
PI:
R.
Tully
PI
Institution:
University
of Hawaii
Accurate
distances can be determined to galaxies if the Tip of the
Red Giant
Branch
(TRGB) can be resolved. The
methodology was taken to a new level of
refinement
with HST/ACS, with distances accurate to 5% obtained for galaxies
at
8 Mpc with single orbit observations. Given multiple orbit observations,
distances
can be obtained for galaxies as
remote as the Virgo Cluster. There
are
now a tremendous number of images in the HST archive that can be used
for
TRGB
measurements. Many were obtained expressly for this purpose but many
more
were
taken for other reasons. While the
TRGB method has been demonstrated to
give
accurate distances, systematic effects can dominate if the data is not
analyzed
in a coherent manner. The authors
of this proposal have recently
developed
an end-to-end analysis procedure that they have been applying to
data
acquired in the course of their own program. Now that ACS is not
available,
there will be less new material entering the archive.
It is an
appropriate
time to process all the available images and recover consistent
TRGB
measurements and distances for all nearby galaxies observed with HST.
======================================================================
Proposal
Category: AR
Scientific
Category: QUASAR ABSORPTION LINES AND IGM
ID:
11286
Title:
Lyman
continuum Absorption and the IGM Opacity at low Redshifts
PI:
David
Tytler
PI
Institution:
University
of California - San Diego
We
will measure the amount of Lyman continuum absorption in the universe at
0.5
< z < 2.5 three times more accurately than currently published
results,
which
have errors of 30%. We will work
with FOS high dispersion spectra of
134
QSOs, FOS low dispersion spectra of 42 QSOs, STIS low dispersion spectra
of
79 QSOs and ACS spectra of 36 QSOs. We expect to detect approximately
155
Lyman
limit absorption systems (LLS) towards these QSOs.
Published work uses
approximately
17 LLS at these redshifts from HST spectra. The
list of LLS
have
many uses, since these systems are amongst the best places to measure
ionization
and abundances, they include likely COS targets. We will derive the
LLS
density, per unit redshift, which is a key input to calculations of the
intensity
of the cosmic UV background. We use the optical depths in the Lyman
continuum,
and fits to Lyman series in the best spectra, to obtain the
distribution
of the H I column densities of the LLS, and especially the
partial
LLS with optical depth < 1. The UV background is required to
understand
the ionization of the intergalactic medium and the gas in the outer
regions
of galaxies that causes QSO absorption lines. It is also needed to run
realistic
simulations which are the key to understanding the IGM and QSO
absorption
systems.
======================================================================
Proposal
Category: AR
Scientific
Category: COSMOLOGY
ID:
11287
Title:
Fundamental
Limitations in deep HST Fields: Surface
Brightness, Natural Confusion, & Algorithmic Biases
PI:
Rogier
Windhorst
PI
Institution:
Arizona
State University
In
the last decade, 1000's of orbits were invested in deep HST surveys. The
HUDF,
HDF, GOODS, GEMS and COSMOS resulted in many new discoveries, ranging
from
dwarf galaxies at the end of reionization to the hierarchical formation
of
galaxies. At the same time, the fundamental limitations in these surveys
may
not have been explored or quantified well enough to fully understand
their
impact. For instance, while deep surveys
for faint galaxies with HST are
obviously
limited by surface brightness (SB) constraints, at the faintest HST
limits
other effects also begin to play a dominant role. First, the rapid
decline
in galaxy sizes at fainter fluxes -- reflecting their hierarchical
assembly
-- may result in a significant fraction being point sources at the
HST
diffraction limit (<0.08" FWHM), hence affecting their selection and
preventing
reliable size measurements. More seriously, natural confusion may
overtake
SB-selection as the dominant selection factor at faint fluxes.
Natural
confusion occurs when there are fewer than a minimum number of "object
beams"
(with area = pi . r_e^2) for each detected (extended) object, analogous
to
the role of the telescope FWHM in the classical instrumental confusion
limit.
Last, various systematics in the parameter determination algorithms can
bias
the results from deep HST surveys in rather uncharted ways. This
Archival
project will quantify these fundamental issues as follows:
(1) run
very
high-resolution hierarchical simulations of the expected object sizes
for
AB<31
mag; (2) simulate effects from the HST-PSF, charge-diffusion, multi-
drizzle,
and CCD-noise on the measured object sizes; (3) simulate how object
finding
and deblending algorithms affect measured fluxes and sizes; (4)
identify
corrections for size overestimation (noise) and underestimation (SB-
dimming);
and (5) delineate the exact locus of the natural confusion limit,
and
determine if and how it overtakes SB as the major cause of
incompleteness
in
HST surveys for AB>24-28 mag.
======================================================================
Proposal
Category: AR
Scientific
Category: COSMOLOGY
ID:
11288
Title:
PASS:
Paying
Attention to the Small Structure
PI:
Roger
Blandford
PI
Institution:
Stanford
University
One
of the main predictions of the Cold Dark Matter (CDM) cosmology is the
existence
of structure formations on all mass scales. Gravitational lensing
offers
a powerful tool for exploring dark matter distributions.Weak-lensing
methods
proved to be a great success in detecting dark-matter large-scale
structure,
but there is still little known about small-scale structures on
sub-galactic
scales. Weak lensing traditionally measures galaxy ellipticities
but
it is clear that there is much more information contained in the galaxy
shapes.
We propose to extend gravitational lensing approach to detect small
scale
structures on cosmological distances using a new method of nonlinear
gravitational
lensing. This method is sensitive to higher derivatives of the
gravitational
potentials (also known as flexions), and can measure mass scales
on
the order of 10^9 Msun to 10^10
Msun. The Ultra Deep Field (UDF)
and a
new
Ultra Deep Field Follow-Up (UDF05) are extremely well suited for
detection
of
nonlinear lensing. Their high resolution is great for measuring the
details
of
galaxy shapes. They also provide a detection of large number of
background
galaxies
necessary for statistical measurements. We will construct our own
super
image of the fields, so that we can also model PSFs in the same frame,
using
the empirical library PSFs. These
PSFs will allow us to better model
the
true morphology of the background galaxies. The images and PSF models
created
within the framework of this proposal will be made publicly available.
======================================================================
Proposal
Category: SNAP
Scientific
Category: COSMOLOGY
ID:
12289
Title:
SL2S: The Strong Lensing Legacy Survey
PI:
Jean-Paul
Kneib
PI
Institution:
Observatoire
de Marseille
Recent
systematic surveys of strong galaxy-galaxy lenses (CLASS, SLACS, GOODS,
etc.)
are producing spectacular results for galaxy masses roughly below a
transition
mass M~10^13 Mo. The observed lens
properties and their evolution
up
to z~0.2, consistent with numerical simulations, can be described by
isothermal
elliptical potentials. In contrast, modeling of giant arcs in X-ray
luminous
clusters (halo masses M >~10^13 Mo) favors NFW mass profiles,
suggesting
that dark matter halos are not significantly affected by baryon
cooling.
Until recently, lensing surveys were neither deep nor extended enough
to
probe the intermediate mass density regime, which is fundamental for
understanding
the assembly of structures. The CFHT Legacy Survey now covers
125
square degrees, and thus offers a large reservoir of strong lenses
probing
a
large range of mass densities up to z~1. We have extracted a list of 150
strong
lenses using the most recent CFHTLS data release via automated
procedures. Following our first SNAPSHOT proposal
in cycle 15, we propose to
continue
the Hubble follow-up targeting a larger list of 130 lensing
candidates. These are intermediate mass range
candidates (between galaxies
and
clusters) that are selected in the redshift range of 0.2-1 with no a
priori
X-ray selection. The HST resolution is necessary for confirming the
lensing
candidates, accurate modeling of the lenses, and probing the total
mass
concentration in galaxy groups up to z~1 with the largest unbiased
sample
available
to date.
======================================================================