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: http://hea-www.harvard.edu/REU/projects07.html
Дата изменения: Unknown Дата индексирования: Mon Oct 1 20:55:56 2012 Кодировка: Поисковые слова: infrared |
------- Text of originally proposed project is not available.
1) Eric Baxter's project abstract
PROJECT TITLE: Spitzer
ADVISORS: Dr. Gus Covey, Dr. August Muench
INTERN: Eric Baxter
------- Advisor's project abstract:
Stellar variability is the key to understanding many stellar
systems. Pulsations provide information about the state of a star;
orbital effects can be used to measure stellar masses; star spots and
even clouds in the atmospheres of low-mass dwarfs also cause
variability. During recent years, the microlensing teams have
monitored tens of millions of stars. Their data sets contain records
of the variability of many types. Some of these observations have been
exploited already; for example Cepheids and eclipsing binaries have
been well studied. The more subtle types of variability have yet to be
explored. We have carried out a preliminary analysis of the MACHO data
set and find evidence of possible new types of stellar
variability. The project we propose would involve a systematic
examination of this variability using the techniques of wavelet
analysis. On the scientific side, the results could have implications
fore the study of stellar systems, since several percent of all stars
in our sample show unusual variability. On the technical side, the
results will be to provide a new tool for the study of variability,
one which can be applied to a wide range of data sets. This will
prepare us for the huge influx of data from the new surveys like
Pan-STARRS and LSST. This work will be done in collaboration with the
Initiative of Innovative Computing at Harvard University.
2) Iara Cury's project abstract
PROJECT TITLE: Stellar Variability in the MACHO Data Set
ADVISORS: Dr. Rosanne di Stefano, Dr. Pavlos Protopapas
INTERN: Iara Cury
------- Advisor's project abstract:
Massive stars are the dominant ingradients of galaxies.
Throughout their lives they inject enormous amounts of energy and
momentum into the interstellar medium from which all stars
form. Starting with powerful outflows and ending in supernovae which
result in exotic object like neutron stars and pulsars their influence
is far-reaching. However, the births of the massive stars are shrouded
mystery. In studying their origins, we are primarily hampered by their
small numbers, large distances, fast evolution and obscuration by
dust. The SPITZER telescope, using its infrared detector, is able to
peer through the dust and has produced a valuable resource called
GLIMPSE, which is a systematic imaging survey of large portions of our
Galaxy. In the proposed project, a summer student can use this image
database to study the environments of a sample of high-mass
proto-stellar objects (HMPOs) which contain massive stars in the
earliest stages of their lives. We have studied this sample at other
wavelengths and the summer student will get the first glimpse of their
characteristics as imaged by SPITZER. Using images at multiple
wavelengths, we will classify objects in the immediate vicinity of the
luminous HMPOs, identify the most massive and youngest memebers and
study their spatial distribution to understand the nature of star
clusters in their earliest stages.
3) Furqan Fazal's project abstract
PROJECT TITLE: Massive stars are the dominant ingradients of galaxies
ADVISORS: Dr. Sridharan Tirupati, Dr. Quizhou Zhang
INTERN: Furqan Fazal
------- Advisor's project abstract:
Active galactic nuclei (AGN) are among the most energetic astrophysical
phenomena in the Universe. Powered by accretion onto a supermassive
black hole, they are often observed to eject twin jets of particles at
relativistic speeds out to very large distances from their centers.
The Chandra X-ray Observatory has revolutionized our understanding of
the energetic processes involved in AGN, through detailed studies of how
jets interact with their hot-gas environments. In several cases, the
energies of the X-ray gas environments exceed 1060 ergs, and giant
cavities in the X-ray gas are often seen, believed to be the result of
an jet expanding into its ambient medium.
This 10-week project will allow the REU student to (1) learn how to
reduce Chandra data, (2) perform imaging and spectroscopy of the nucleus
and thermal gas of several nearby AGN, and (3) combine these data with
observations at radio and optical wavelengths to better understand the
physical conditions present in active galaxies.
Clusters of galaxies are the most massive gravitationally bound
objects in the universe. They formed relatively recently in the
history of the universe, so we can try to measure their evolution
directly. This project will focus on understanding the evolution of
cluster and galaxy properties in a sample of clusters at moderate
redshift. These clusters have been observed with Chandra, Spitzer, and
ground-based optical telescopes. We will analyze infrared images of
the clusters to identify likely cluster members and estimate the
stellar masses of the galaxies and the clusters. If time allows, we
will compare these properties to the X-ray and mid-infrared properties
of the clusters. These detailed comparisons will be critical for using
future cluster surveys to probe dark energy.
The abundance of clusters and groups in the nearby universe is a
powerful constraint on cosmological parameters. In particular, the
anisotropies seen in the microwave background should grow to form the
clusters we see today. We have used the Sloan survey to measure the
abundance of clusters in the nearby universe, but measuring the
abundance of groups is more difficult. We have begun a survey of
groups outside the Sloan survey region to measure the abundance of
these lower-mass systems. The project will involve compiling the
existing and new data to measure group masses and use these to measure
cosmological parameters. The project may involve an observing run to
Mt Hopkins to operate a telescope and collect some of the data for the
survey.
4) Sarah Harrison's project abstract
PROJECT TITLE: Energetic processes in the environments of Active Galactic Nuclei
ADVISORS: Dr. Dan Evans, Dr. Julia Lee
INTERN: Sarah Harrison
------- Advisor's project abstract:
Clusters of galaxies are the most massive gravitationally bound
objects in the universe. They formed relatively recently in the
history of the universe, so we can try to measure their evolution
directly. This project will focus on understanding the evolution of
cluster and galaxy properties in a sample of clusters at moderate
redshift. These clusters have been observed with Chandra, Spitzer, and
ground-based optical telescopes. We will analyze infrared images of
the clusters to identify likely cluster members and estimate the
stellar masses of the galaxies and the clusters. If time allows, we
will compare these properties to the X-ray and mid-infrared properties
of the clusters. These detailed comparisons will be critical for using
future cluster surveys to probe dark energy.
The abundance of clusters and groups in the nearby universe is a
powerful constraint on cosmological parameters. In particular, the
anisotropies seen in the microwave background should grow to form the
clusters we see today. We have used the Sloan survey to measure the
abundance of clusters in the nearby universe, but measuring the
abundance of groups is more difficult. We have begun a survey of
groups outside the Sloan survey region to measure the abundance of
these lower-mass systems. The project will involve compiling the
existing and new data to measure group masses and use these to measure
cosmological parameters. The project may involve an observing run to
Mt Hopkins to operate a telescope and collect some of the data for the
survey.
5) Colin Hill's project abstract
PROJECT TITLE: Understanding Cluster Evolution / Nearby Clusters and Cosmology
ADVISOR: Dr. Ken Rines
INTERN: Colin Hill
------- Advisor's project abstract:
We are examining the way particles are accelerated and heated as they
propagate from the solar corona to the earth. The student would be
exposed to data from XRT on Hinode, ACE, ULYSSES, and SOHO
satellites. Specifically they would be responsible for fitting
distribution of protons from the ACE, Ulysses and SOHO satellite. Then
they would use the XRT data to compare the initial conditions of these
energetic particles. By fitting the proton particle distributions and
looking at timing, we can get a sense of the changes the plasma
undergoes as it moves through theheliosphere and where it deposits the
energy. The student would be responsible for fitting the data sets and
then helping prepare the paper. The student will get an introduction
to solar physics, some statistical mechanics, data analysis, plasma
astrophysics, image processing, and stellar winds. The student would
also have an opportunity to present the work either at an SSP seminar
or at a monthly meeting of the New England Space Science Consortium.
6) Therese Jones's project abstract
PROJECT TITLE: Particle Acceleration from the Solar Corona to the Earth
ADVISOR: Dr. Kelly Korreck
INTERN: Therese Jones
------- Advisor's project abstract:
The Chandra Multiwavelength Plane (ChaMPlane) survey is a large
project to study the properties of the various classes of
low-luminosity X-ray point sources in our Galaxy. These include
binaries with compact objects like white dwarfs or neutron stars that
accrete gas from a companion star, but also stars like the Sun, and
close binaries where the tidal forces between the stars make them spin
fast. The instruments on the Chandra X-ray Observatory have unique
capabilities to expand our knowledge of these X-ray sources. The
sensitivity of Chandra allows us to detect systems out to large
distances; and thanks to Chandra's unprecedented spatial resolution
the positions of these X-ray sources can be measured with a precision
like never before, which is extremely important for follow-up studies
and source classification. ChaMPlane makes use of archived Chandra
images that were taken when Chandra was looking at objects that lie in
directions close to the Galactic plane. Typically, the astronomers
that have made these images are only interested in one object, but
many more are detected. We process these images and try to classify
all the sources, first by taking optical and near-infrared images to
identify the objects that emit the X-rays, and finally by taking
spectra to determine the source class. Currently, the ChaMPlane X-ray
database includes almost 14000 point sources detected in about 120
discrete fields, that are covered by more than 200 Chandra
observations. Deep optical images in three broad- and one narrow-band
filter (V, R, I and Halpha) have been taken for all of them, and
although far from complete, our spectral database is steadily growing
with classification spectra being taken for more than 2700 candidate
counterparts.
The REU summer internship will allow students to become familiar with
several aspects of the ChaMPlane project. We suggest two possible
projects from which the student can choose:
1) The goal of the first project is to characterize the
properties of the brightest of the ChaMPlane sources. The first phase
involves fitting X-ray spectra, from which we derive constraints on
a) the process that creates the X-ray emission (accretion versus
magnetic activity), and
b) the amount of extinction (and consequently the distance) between us
and the source. Currently there are between 50 and 75 such bright
ChaMPlane sources (excluding sources close to the Galactic Center). In
the second phase, a search for the optical counterparts will be done
using the available optical/infrared data while taking into account
the X-ray constraints on the source classes and distances.
2) Some parts of the Galaxy are heavily obscured by clouds of
dust and gas that prevent us from seeing what is behind them when we
use optical images. The effects of extinction are less severe in the
near-infrared. The ChaMPlane near-infrared images serve to look for
counterparts of obscured X-ray sources, but a lot more can be learned
from them. For example, candidate star clusters, previously identified
by other groups in lower-resolution images, can be studied with a
"sharper view" and a search for more candidate clusters can be
done. Potentially associated X-ray sources can then be used to learn
more about both the clusters and X-ray sources, like their distances
and when/how they were formed. Close examination of the infrared
images can lead to other interesting discoveries (and possible X-ray
counterparts), like planetary nebulae that are formed when a low-mass
star expels its outer layers at the end of its life (in an initial
examination we have already found one new planetary nebula).
The colors of a star are sensitive to the amount of gas and dust
through which we see it. Another application of this infrared project
is to derive a relation between the infrared and X-ray colors of
ChaMPlane sources, which can then be used to constrain an X-ray
source's distance even when no obvious counterpart is found;
information on distances is crucial to study the distribution of X-ray
sources in the Galaxy.
Both projects are suitable for a poster presentation at the January
2008 AAS meeting. Throughout the 10-week period, the student will have
the opportunity to interact with different ChaMPlane group members,
and experience what it is like to be part of a research group. For
more details on ChaMPlane, visit http://hea-www.harvard.edu/ChaMPlane.
7) Kyle Penner's project abstract
PROJECT TITLE: Optical and infrared identifications of ChaMPlane sources
ADVISORS: Dr. Silas Laycock, Dr. Maureen van den Berg
INTERN: Kyle Penner
------- Advisor's project abstract: 8) Megan Reiter's project abstract
PROJECT TITLE: An IRAC view of Galactic Asymptotic Giant Branch Stars
ADVISOR: Dr. Massimo Marengo
INTERN: Megan Reiter
The Sun, towards the end of its life, will become an Asymptotic Giant
Branch (AGB) Star. Once exhausted its primary Hydrogen nuclear fuel,
it will ultimately become 10,000 more luminous than today, and swell
beyond the orbit of our planet, that will be engulfed and
vaporized. This act of destruction, however, will also be an act of
creation: it is in the nuclear furnaces of AGB stars that most of the
carbon, the basic element of life, available in the Galaxy is
synthesized. This carbon, together with other heavy elements, is
slowly released to the circumstellar environment in the form of a
dusty wind, that gradually surrounds the star with a thick opaque
cocoon. Like a butterfly from the chrysalis, the cocoon will
ultimately burst to give rise to a Planetary Nebula, one of the most
beautiful and ephemeral objects in the sky, leaving behind a white
dwarf. The carbon and the other elements released in the AGB wind will
merge with the interstellar medium, ready for a new cycle of stellar
and planetary formation: the carbon atoms in our body have likely been
produced in an AGB stars billion of years ago.
------- Text of originally proposed project is not available.
9) Blake Sherwin's project abstract
PROJECT TITLE: Hypervelocity Stars from the Andromeda Galaxy
ADVISOR: Dr. Avi Loeb
INTERN: Blake Sherwin
------- Advisor's project abstract:
We have embarked on a multiwavelength program to study the relation
between galaxy interactions and the level and type of activity they
induce. The main element of this program is Spitzer multiband imaging
and spectroscopic observations of a large sample of nearby interacting
galaxies. These data provide a view of the evolution of star-formation
and AGN activity as a function of the stage and the parameters of the
interaction. An independent picture of the activity in a subset of
these galaxies, is given by X-ray observations, which provide
diagnostics for the presence of AGNs and they allow us to study the
evolution of X-ray binaries and hot gas in the different stages of
galaxy interactions.In total 18 systems from the Spitzer sample have
been observed with Chandra. These systems span the full range of
interaction stages from weak interactions to coalescing galaxies. In
particular the Chandra data will allow us to investigate: (a) how the
discrete source and diffuse X-ray emission components evolve in the
different stages of the interaction; (b) address the connection of
Ultra-luminous X-ray sources with enhanced star-formation; (c) study
the X-ray emission from the nuclei and search for the presence of
AGNs. We will measure as a function of the merger stage: the relative
contribution of the diffuse emission and the discrete sources in the
overall X-ray emission of the systems; their relation with IR, optical
and radio emission; the spectral parameters of the diffuse emission
and the luminosity distribution of the discrete sources. Comparison
with the already analyzed Spitzer data will identify emission
components related with on-going star-formation. A student who will
work on this project will learn how to analyze X-ray data using
existing and previously tested software (CIAO, Sherpa), and perform
comparisons between the X-ray, infrared and optical data. There are
ready made scripts and tasks to do parts of this analysis which will
be used by the student (after of course the required training). They
will also analyze Spitzer data (as needed) again using existing and
previously tested software. Since the overall sample is too large to
be analyzed in such a short period of time, the student will focus on
a subset of 10 objects with good quality Chandra data, spanning the
full range of interaction parameters (the actual size of the sample
can be adjusted depending on the progress of the student). The main
focus will be on the analysis of the Chandra data and the comparison
with data in other wavebands. This way the student will be exposed to
the interpretation of scientific data and learn about galaxy
interactions, star-formation and sources of X-ray emission in
galaxies. They will be introduced to the physical mechanisms of
emission in different wavebands and the different diagnostics we use
in order to distinguish between them. Finally they will learn how to
do background literature research on a specific topic.
0) Johanna Teske's project abstract
PROJECT TITLE: A combined Chandra/Spitzer study of galaxy mergers
ADVISOR: Dr. Andreas Zezas
INTERN: Johanna Teske
1) Eric Baxter
Harvey Mudd College
--- Advisor: Dr. Gus Covey, Dr. August Muench
The Distance to NGC 2264 (No abstract available.)
--- Advisor: Dr. Rosanne di Stefano, Dr. Pavlos Protopapas
Needles in a haystack--Looking for Overlooked MACHO Events (No abstract available.)
Spectral Energy Distribution of High-Mass Protostellar Objects - Evidence for High Accretion Rates (No abstract available.)
--- Advisor: Dr. Sridharan Tirupati, Dr. Quizhou Zhang
X-ray and Radio Observations of the Jet--Environment Interaction in 3C 123
--- Advisor: Dr. Dan Evans, Dr. Julia Lee
The Virial Mass Function of Nearby Galaxy Groups and Clusters (No abstract available.)
--- Advisor: Dr. Ken Rines
Suprathermal Heavy Ion Distributions in Shocks Driven by Interplanetary Coronal Mass Ejections (No abstract available.)
--- Advisor: Dr. Kelly Korreck
The Brightest Serendipitous X-ray Sources in CHAMPLANE (No abstract available.)
--- Advisor: Dr. Silas Laycock, Dr. Maureen van den Berg
An IRAC Characterization of AGB Stars (No abstract available.)
--- Advisor: Dr. Massimo Marengo
Hypervelocity Stars from the Andromeda Galaxy (No abstract available.)
--- Advisor: Dr. Avi Loeb
Observation of Galaxy Mergers with Chandra and Spitzer (No abstract available.)
--- Advisor: Dr. Andreas Zezas