TITLE: Scattered Light Mapping of Debris Disks

ID: 93020

GOAL: Spatially resolved, scattered light maps of debris disks can be used to constrain dust properties (composition, size, distance from central star) and therefore to infer the dynamics of dust grains and place constraints on the presence of low mass planets at large distances in exo-planetary systems. The JWST/NIRCam medium band filter set is expected to provide (for the first time) high resolution, high contrast imaging in the 3 mm water ice feature and at wavelengths > 4 mm. It will provide long-wavelength constraints on the scattered light SEDs of debris disks to determine the composition of dust grains and in particular allow mapping of water ice grains in debris disks as a function of position to determine the location of the snow line. Since the NIRCam coronagraph performance is expected to be approximately commensurate with that obtained by HST/ACS on-flight, initial NIRCam coronagraph observations of debris disks will focus on detailed characterization of disks that have already been detected and resolved in scattered light.

This program will obtain spatially resolved scattered light maps for a subset of 14 well studied, spatially resolved debris disks using NIRCam Coronagraphy in four filters: F210M, F300M, F335M, and F430M. The F210M and F335M filters will provide measurements of the disk surface brightness at wavelengths adjacent to the 3.0 mm water ice band (F300M) to determine whether an absorption feature is present. The measured surface brightness in the F430M filter can be compared with surfaced brightnesses measured using HST ACS, NICMOS, and STIS to measure the reflected light color and further constrain the composition of the dust. Since the central star is expected to be very bright compared to the faint disk surface brightness, all observations will be obtained in coronagraphic mode, using the sombrero-squared circular occulters.

TARGET(S):

OBSERVING TEMPLATES:

NIRCam Coronagraphy

OBSERVATION DETAILS:

Simulations of NIRCam coronagraphic performance suggest that bright disks, with fractional infrared luminosities, LIR/L_* > 1.6x10^-4, can be detected and spatially resolved in 5000 sec of exposure time (Krist et al. 2011). All of the targets proposed here are bright and the majority have fractional infrared luminosities larger than this fiducial target; therefore, we have assumed 5000 sec integration times for each of the proposed targets in each proposed filter.

Each NIRCam Coronagraphy target will be observed with the Mask210R/F210M, MASK335R/F300M, MASK335R/F335M, and MASK430R/F430M mask/filter combinations to map dust grain color as a function of position in the disk. Each target is observed at two telescope rolls. Including both rolls, each point in the FOV will possess a total observation time ~5000 sec per filter.

Since the JWST mirrors will be phased every two weeks, we have included observations of reference stars immediately before or after each of our NIRCam observations. Since the PSF is expected is change substantially at near-infrared wavelengths, observations of reference stars are critical for good PSF subtraction. Reference stars were selected to possess similar spectral types and V-band magnitudes as the target star and to be located within 10° of the target. The reference stars selected here are preliminary and do not necessarily possess optimum V-K color matches that are necessary for short wavelength NIRCam coronagraphy.

CONSTRAINTS:

Reference star observations must be executed back-to-back with target observations. Comment "SAME OBSERVATION" has been added on each Observation folder to indicate this. In addition, MIRI Coronagraphy observations possess orientation constraints on the target to ensure that the edges of the 4QPM or the bar in the Lyot Coronagraph do not overlap with disk structures. The two roll angle observations of targets in MIRI Coronagraphic mode must be offset by >8° to minimize the occulted region in both rolls.

PARALLEL Observations possible (yes/no/pure parallel)?

N/A

PROGRAM COORDINATOR/DATE: D. C. Hines/12 December 2011

For more information about this program refer to the latest version of the SODRM.

TITLE: Thermal Emission Mapping of Debris Disks

ID: 93021

GOAL: Spatially resolved, thermal emission maps of debris disks can be used to constrain dust properties (composition, size, distance from central star) and therefore to infer the dynamics of dust grains and place constraints on the presence of low mass planets at large distances in exoplanetary systems. The excellent sensitivity and angular resolution of JWST/MIRI is expected to enable thermal emission mapping of nearly all debris disks around A-type stars within ~100 pc (Smith & Wyatt 2010); however, the overheads associated with observing are expected to be sufficiently high that the initial MIRI imaging observations of debris disks will focus on detailed characterization of already spatially-resolved disks. To date, approximately 15-20 debris disks have been spatially resolved in scattered light using HST and ~50 debris disks have been spatially resolved in thermal emission using space-based (Spitzer and Herschel) and ground-based (Gemini and VLT) facilities.

This program will obtain spatially resolved thermal emission maps for a subset of 20 well studied, spatially resolved debris disks using MIRI Imaging and Coronagraphy in two filters. Two is the minimum number of filters required to map disk color as a function of position. Debris disks around stars with Fn(24 mm) > 0.8 Jy are expected to saturate rapidly the MIRI detector in direct imaging mode and will therefore be observed using the MIRI Four Quadrant Phase Mask and Lyot Coronagraphs. Debris disks around stars with Fn(24 mm) < 0.8 Jy are expected to be sufficiently faint that they can be observed in direct imaging mode, requiring less observatory time for target acquisition and fewer scheduling constraints.

TARGET(S):

Well-characterized, spatially resolved debris disks in scattered light:

• HD 141569
• HR 4796
• HD 32297
• Fomalhaut
• beta Pic
• HD 15745
• HD 15115
• HD 181327
• HD 139664
• HD 10647
• HD 107146
• HD 61005
• HD 53143
• HD 92945
• AU Mic.

Subset of currently known, spatially resolved debris disks in thermal emission:

• epsilon Eri
• Vega
• gamma Oph
• beta Leo
• beta UMa

OBSERVING TEMPLATES:

MIRI Coronagraphy
MIRI Imaging

OBSERVATION DETAILS:

Since all of our targets have observed using Spitzer (IRS and MIPS), the 15 and 25.5 μm brightness of their central stars and the 15 and 25.5 μm unresolved disk fluxes have been measured. The approximate surface brightness of the disk can be estimated, SB = Fex(25.5 mm)/(πD² ), where D is the measured angular size of the disk from either scattered light or thermal emission imaging. We estimate typical 25.5 mm surface brightnesses ~0.01-20 mJy/arcsec² for disks that are already spatially resolved at mid- to far-infrared wavelengths. We design the MIRI Imaging observations to obtain a SNR ~95 and ~25 for a disk with average surface brightness ~0.01 mJy/arcsec² at 15.0 and 25.5 mm, respectively. We design the MIRI Coronagraphic observations to obtain a SNR ~9 and ~33 for a disk with average surface brightness ~0.01 mJy/arcsec² at 15.5 and 24.0 mm, respectively.

Imaging: Each MIRI Imaging target will be observed with F1500W and F2550W filters using the FULL array to map dust grain color as a function of position in the disk. Each Imaging observation is dithered to mitigate for bad pixels using a subset of 5 points from the Cycling/Medium pattern. Including dithering, each point in the FOV will possess a total observation time 555 sec.

Coronagraphy: Each MIRI Coronagraphy target will be observed with the F1550C Four Quadrant Phase Mask and the F2300C Lyot Coronagraph to map dust grain color as a function of position in the disk. Each target is observed at two telescope rolls. Including both rolls, each point in the FOV will possess a rolls. Including both rolls, each point in the FOV will possess a total observation time 728.8 sec and 1033.6 sec at 15 μm and 25.5 μm, respectively.

Since the JWST mirrors will be phased every two weeks, we have included observations of reference stars immediately before or after each of our MIRI observations; however, the MIRI observations requested here are at such long wavelengths that they may be insensitive to mirror phase changes. Reference stars were selected to possess similar spectral types and V-band magnitudes as the target star and to be located within 10° of the target (if possible).

CONSTRAINTS:

Reference star observations must be executed back-to-back with target observations. Comment ''SAME OBSERVATION'' has been added on each Observation folder to indicate this. In addition, MIRI Coronagraphy observations possess orientation constraints on the target to ensure that the edges of the 4QPM or the bar in the Lyot Coronagraph do not overlap with disk structures. The two roll angle observations of targets in MIRI Coronagraphic mode must be offset by >8° to minimize the occulted region in both rolls.

PARALLEL Observations possible (yes/no/pure parallel)?

N/A.

COMMENTS:

This is a program that is similar to a debris disk imaging program that was discussed by the MIRI Science Team (discussion lead by K. Su and G. Rieke) that focuses on resolving disk structures indicative of the presence of planets and/or tracing out the snowline in debris disks.

There are currently 50+ debris disks that have been resolved in either scattered light (HST) or thermal emission (Gemini, Herschel, Spitzer, VLT) imaging and many more debris disks are expected to be resolved using future facilities (e.g. Gemini/GPI and VLT/SPHERE); therefore, this program could easily easily be expanded by a factor of a few.

PROGRAM COORDINATOR/DATE: C. Chen, D. Hines, J. Muzerolle/27 Jan 2012

For more information about this program refer to the latest version of the SODRM.

TITLE: Thermal Emission Spectroscopy of Debris Disks

ID: 93022

GOAL: Mid-infrared spectroscopy of debris disks can be used to constrain dust properties (composition, size, crystallinity) and therefore to infer the nature of parent bodies and the evolutionary status of debris disks. For example, detailed analysis of the Spitzer IRS spectrum of HD 172555, an A7V member of the ~12 Myr β Pictoris Moving Group, has revealed the presence of glassy silicas found in impact and magmatic systems and possible SiO gas, indicating the presence of a recent giant, collision (Lisse et al. 2009). By contrast, detailed analysis of the spectrum of η Crv, a ~1.4 Gyr old F2V main sequence star, has revealed the presence of water and carbon-rich dust that may have been delivered to the inner Solar System by a primitive Kuiper Belt Object (Lisse et al. 2011). The excellent sensitivity and angular resolution of JWST/MIRI is expected to enable spectroscopic mapping of debris disks to search for gradients in grain properties that may be expected if debris disks possess multiple parent bodies belt or if dust grains are dynamically sorted by size (for example). The excellent spectral resolution of JWST/MIRI will enable sensitive searches for molecular and atomic gas that may either by the remnant of primordial gas or second-generation gas produced from the dust.

This program will obtain MIRI MRS (R~3000) spectra of (1) 10 debris disk systems with Spitzer IRS identified 10 μm silicate emission features to carry out detailed spectroscopic analysis of the dust, search for variability and SiO gas emission that may further indicate that giant collisions have occurred in these systems and (2) 4 spatially resolved debris disk systems to measure directly the SEDs of individual belts in multiple belt systems and to search for gradients in grain properties as a function of position. The spectra will be obtained using ALL three MRS grating settings to provide complete spectral coverage over the MIRI MRS wavelength range (5.0-30 μm).

TARGET(S):

Silicate Feature Targets:

Multiple Dust Belt Targets:

OBSERVING TEMPLATES:

MIRI MRS-IFU

OBSERVATION DETAILS:

Since all of our targets have been observed using Spitzer (IRS and MIPS), the brightnesses of their central stars and the unresolved brightnesses of the disks have been measured. The approximate surface brightness of the disk can be estimated, SB = Fex(24 mm)/(πD²), where D is the measured angular size of the disk from either scattered light or thermal emission imaging.

We estimate typical 24 mm surface brightnesses ~1-20 mJy/arcsec² for disks that possess 10 μm spectral features or are very bright and extended. We design the MIRI MRS observations to obtain a SNR ~12 for a disk sign the MIRI MRS observations to obtain a SNR ~12 for a disk with with average surface brightness ~1 mJy/arcsec² at 22.5 mm.

Each MIRI MRS target will be observed with ALL of the grating settings. For each grating setting, each point in the MRS FOV will possess a total observation time 555 sec.

At the current time, the observations include only one MRS field-of-view (FOV) per target; however, spatially resolved targets will need to be mapped by stitching multiple MRS FOVs together. In addition, for each FOV, the target should be dithered over a four-point pattern to improve spatial sampling in the sub-slice direction and to improve sub-pixel sampling in the dispersion direction for Channel 1.

Since the JWST mirrors will be phased every two weeks, we have included observations of reference stars immediately before or after each of our MIRI observations especially since accurate subtraction of the PSF at the shortest wavelengths may be necessary to reveal the spectrum of warm dust and gas. Reference stars were selected to possess similar spectral types and V-band magnitudes as the target star and to be located within 10° of the target (if possible).

CONSTRAINTS:

Reference star observations must be executed back-to-back with target observations.

PARALLEL Observations possible (yes/no/pure parallel)?

N/A.

COMMENTS:

This is a program that is similar to a debris disk spectroscopy program that was discussed by the MIRI Science Team (discussion lead by K. Su and G. Rieke) that focuses on young debris disks that may be experiencing giant collisions during the end stages of terrestrial planet formation and on mapping silicate emission features in bright, extended disks.

To date, approximately 15-20 debris disks have been spatially resolved in scattered light using HST and ~50 debris disks have been spatially resolved in thermal emission using space-based (Spitzer and Herschel) and ground-based (Gemini and VLT) facilities. Many of these systems are large compared to the MRS Channel 1 and/or show evidence for multiple dust belt populations; therefore, this program could be expanded by a factor of 2-3.

PROGRAM COORDINATOR/DATE: D. C. Hines/12 December 2011

For more information about this program refer to the latest version of the SODRM.

TITLE: Imaging of Galactic Massive Star Forming Regions and Young Clusters

ID: 93060

GOAL: This program will survey young massive clusters and star forming regions in the Milky Way, with the goal of determining YSO classifications and characterizing circumstellar disk emission for the full stellar mass range (and, in many cases, into the brown dwarf regime). A total of 11 regions have been selected, with distances ranging from ~ 2 to 7 kpc. The sample includes a range of cluster sizes, from thousands to tens of thousands of stars, and apparent ages ranging from <1 to ~5 Myr. The NIRCam images will be used primarily for characterization of very young and low mass stellar objects, as well as target identification for follow-up NIRSpec MSA observations (using the F187N filter in order to measure positions for the brightest possible stars). We selected 6 MIRI broad band filters in order to sample both dust continuum emission and 10 and 18 μm silicate features for the most detailed possible spectral energy distributions of protostars and Class II possible spectral energy distributions of protostars and Class II disked stars.

TARGET(S):

• NGC 3603
• RCW 49
• M 16
• M 17
• Westerlund 1
• NGC 3576
• W43
• W51A/B

OBSERVING TEMPLATE:

NIRCam imaging
MIRI imaging

OBSERVATION DETAILS:

Each region will be observed with the NIRCam and MIRI imagers, with mosaics covering the relevant areas (typically ~ 5'- 10'; see attached figure for an example). Short exposures will be used for all NIRCam filters in order to mitigate against saturation, but which ensure detection of stellar photospheres at all wavelengths for objects below the substellar limit in all target regions. Exposure times for MIRI imaging were estimated with the goal of reaching the stellar photosphere of a 1 Myr-old 0.1 Msun star at 5 kpc with S/N > 10 at 5-10 μm.

NIRCam setup:

• short/long filters: F090W/F277W, F115W/F356W, F150W/F444W, F187N/F480M
• both modules, full array, 3TIGHT primary dither with 3 subpixel positions
• mosaics with 2-4 rows, 1 column, 10% overlap
• RAPID readout, 3 groups, 1 integration for each filter

MIRI setup:

• filters: F560W (FAST readout, 2 groups/int.), F770W (FAST readout, 4 groups/int.), F1000W (SLOW readout, 6 groups/int.), F1500W (SLOW readout, 6 groups/int., F1800W (SLOW readout, 6 groups/int.), F2550W (FAST readout, 6 groups/int.)
• full array, cycling 5pt dither pattern
• 10 integrations per exposure for F2550W, 1 int./exp. for all other filters
• mosaics sized for each target region, 10% row/column overlap

Two observations per target, one for each instrument. The observations are collected into separate observation folders. The total time estimate was calculated assuming that the 30 min. target slew would be charged to each of the two observations of each target. However, a single slew with observations by both instruments in sequence, would be more efficient, saving approximately 5.5 hours.

PARALLEL Observations possible (yes/no/pure parallel)?

no

COMMENTS:

The target sample is a representative selection, mostly chosen to span parameter space and require relatively small mosaics to cover.

PROGRAM COORDINATOR/DATE: J. Muzerolle/1s42 December 2011

For more information about this program refer to the latest version of the SODRM.

TITLE: MOS Spectroscopy of Galactic Massive Star Forming Regions and Young Clusters

ID:93061

GOAL:

This program will follow up the photometric survey of young massive clusters and star forming regions in the Milky Way done in program 3060 by obtaining near-infrared spectra of a representative sample of stars from each region. The primary goals will be to determine spectral types and characterize stellar mass accretion and circumstellar disk emission for the full stellar mass range (and, in most cases, well into the brown dwarf regime). Spectroscopic targets will be selected from the same 11 regions observed in 3060, with distances ranging from 2 to 7 kpc, cluster sizes ranging from a few to ten thousand stars, and apparent ages ranging from <1 to ~5 Myr. The total number of targets for each region will be commensurate with the cluster size and selected in order to provide a statistical sampling of the mass function.

ACTUAL TIME (hours): 325

TARGET(S):

• NGC 3603
• RCW 49
• M 16
• M 17
• Westerlund 1
• NGC 3576
• W43
• W51A/B

OBSERVING TEMPLATE:

NIRSpec MSASPEC

OBSERVATION DETAILS:

These observations are ideally suited to the NIRSpec MSA. Accurate coordinates for individual stellar targets, as well as reference stars for target acquisition, would be measured from the appropriate NIRCam images observed in program 3060. The dynamic range in brightness for these regions is extremely large (depending on the level of dust extinction, some 8 magnitudes or more separate the intermediate-mass stars from the brown dwarfs), so the samples must be broken up into separate brightness bins in order to avoid significant saturation. For this exercise, we assumed that putative candidate sets for each region would be split into two magnitude bins, ''bright'' and ''faint''. Roughly 100/500 stars in the bright/faint bin should be feasible with 3/10 MSA target sets, respectively, which would provide a minimum statistical sampling in the most populous clusters of the sample. Each target set requires two MSA configurations because a wavelength gap-filling dither is 26 configurations for each region (6 bright and 20 faint); in reality, some regions would require more and some fewer depending on the stellar density and overall spatial extent, but this should provide a reasonable average estimate.

NIRSpec setup:

• gratings/filters: G140M/F100LP, G235M/F170LP
• 3-shutter slitlet pattern for each target, with appropriate dithers to nod the targets between each shutter (i.e., ''NNOD=2'')
• the wavelength gap must be recovered (''WAVEGAP=yes'')
• bright target exposures: NRSRAPID readout, NGROUP=3, NINT=1
• faint target exposures: NRS readout, NGROUP=14, NINT=1

PARALLEL Observations possible (yes/no/pure parallel)?

no

COMMENTS:

PROGRAM COORDINATOR/DATE: J. Muzerolle/9 January 201s21

For more information about this program refer to the latest version of the SODRM.

TITLE: Imaging and Coronagraphy of Protoplanetary Disks

ID: 93070

GOAL: Spatially resolved imaging of protoplanetary disks at a wide range of wavelengths will provide unprecedented constraints on dust grain growth and radial structure. The target sample is split into edge-on disks, which can be observed with direct imaging, and brighter less-inclined objects that must be observed with coronagraphy.

NOMINAL ALLOCATION (hours):

300

TARGET(S):

• HV Tau C
• HK Tau B
• DG Tau B
• V1213 Tau
• 2MASS J04331650_2253204
• 2MASS J15491551-2600501
• Gomez' Hamburger
• Orion 114-426
• LkHa 263 C
• 2MASS J16281370- 2431391 (''Flying Saucer'')

coronagraphic disks:

• GG Tau
• FN Tau
• GM Aur
• HL Tau
• V1079 Tau
• UY Aur
• AA Tau
• CI Tau
• CY Tau
• DM Tau
• DO Tau
• TW Hya
• HD 31293
• HD 36910
• HD au
• CI Tau
• CY Tau
• DM Tau
• DO Tau
• TW Hya
• HD 31293
• HD 36910
• HD 100546
• CD 36-10010B
• HD 142527
• HD 150193
• HD 169142
• HD 97048
• HD 319139
• HD 31648
• IM Lup
• MP Mus
• V1032 Cen
• 2MASS J04324303+2552311
• 2MASS J16270233-2437272
• V1121 Oph
• BP Psc

OBSERVING TEMPLATE:

NIRCam imaging
MIRI imaging
NIRCam coronagraphy MIRI coronagraphy

OBSERVATION DETAILS:

The times in this program are still quite schematic, particularly for the coronagraphic specifications. The time estimate was calculated using a single prototype source for each part; in reality the sample will span a wide range of fluxes. However, the overheads largely dominate.

NIRCam imaging:

• Short/long filters: F070W/F277W, F115W/F356W, F150W/F444W, F200W/F480M
• 128x128 subarray
• duration per target = 0.35 hr

MIRI imaging:

• Filters: F560W, F1000W, F1500W, F2550W FAST readout, 38 groups/int.
• 5pt Gaussian dither pattern with subpixel sampling
• duration per target = 1 hr

NIRCam coronagraphy:

• 210R, 335R, 430R masks
• RAPID readout, 10 groups/int., 1/4/12 int./exp.
• Reference star observations
• duration per target = 1.2 hrs

MIRI coronagraphy:

• 4-quadrant phase masks with F1065C, F1140C, F1550C filters
• reference star observations
• included 2 dither movements and TAs for placement of targets
• in two directions duration per target = 6.8 hrs

PARALLEL Observations possible (yes/no/pure parallel)?

no

COMMENTS:

Note that the ''SAME OBSERVATION'' comment has been added on the coronagraphy observations to keep the target and reference star observations together. The imaging portion of this program would also benefit by a capability for multi-instrument (sequential) observations of the same target. There is a reason to at least keep the imaging observations close in time to avoid impacts from stellar variability, but back-to-back observing is not a requirement.

PROGRAM COORDINATOR/DATE: J. Muzerolle/Feb 03, 2012

For more information about this program refer to the latest version of the SODRM.

TITLE: JWST survey of the Orion Nebula

ID: 93080

GOAL: We will use NIRCAM and MIRI to survey the Orion Nebula Cluster, the richest young stellar cluster in the solar vicinity (414 pc), over an area comparable to the HST Treasury Program at optical wavelengths. We will obtain a complete, unbiased sample of thousand of circumstellar disks in a variety of environments and evolutionary status, e.g. photoevaporated by external UV radiation (proplyds), by their central stars, or in a relatively quiescent status more germane to planet formation. The IR SEDs, reconstructed from 1 to 26 μm, will allow us to constrain the disk structure (flaring angle, gaps, dust settling,...) from a few stellar radii to beyond the habitable zone. We will use color-color diagrams to disentangle the population of young stars from reddened background sources and then reconstruct a reliable, unbiased IMF of the cluster, analyzing its variation vs. the distance from the center. We will discover an unknown but presumably significant number of infrared companions and free floating ''Jupiters'' down to 1 MJup. We will also trace embedded jets and HH objects from the youngest protostars, dusty ''cometary tails'' of photoevaporated mass loss, high density Class 0 cores, etc.

NOMINAL ALLOCATION (hours):

100

TARGET(S):

M42 (Orion Nebula)

OBSERVING TEMPLATE:

NIRCam Imaging

OBSERVATION DETAILS:

NIRCAM;

MIRI parallels would reduce the total observing time.

COMMENTS:

For the MIRI wide field survey we require only 1 small dither move for bad pixel removal.

PROGRAM COORDINATOR/DATE: M. Robberto/Feb. 10, 2012

For more information about this program refer to the latest version of the SODRM.

TITLE: The Initial Mass Function at Sub-Stellar Masses

ID: 93090

GOAL: Our proposed NIRCam survey will discover and characterize the substellar population (down to ~13MJup, the D-burning limit) in a variety of astrophysical environments. Understanding the initial mass funcion (IMF) of brown dwarfs is critical to clarify the role of D-burning vs. gravothermal contraction and accretion. These are the main mechanisms controlling the energy output of protostar and regulate the relative invariance of final stellar masses. We will use color magnitude and 2-color diagrams in F115W, F140M and F162M filters to determine Av , Teff and memberships across the whole BD domain. By probing 15 cornerstone regions of different age, environmental conditions and metallicity we will analyze how the IMF, and the characteristic stellar mass, may vary with the galaxy type and across the history of the universe.

TARGET(S):

• LH95
• NGC3603
• 30Dor core
• Westerlund 1
• W3
• Arches
• W51
• W2
• NGC602
• NGC346
• Omega Cen
• 47Tuc
• S106
• N80
• MonR2

OBSERVING TEMPLATE: OBSERVATION DETAILS:

Yes, MIRI

Exposure times could be tuned to the distance of the target.

PROGRAM COORDINATOR/DATE: M. Robberto/Nov.30, 2011

For more information about this program refer to the latest version of the SODRM.

TITLE: Revealing Outflows, Disks and Accretion Processes in High Mass Protostellar Objects (HMPOs)

ID: 93100

GOAL: In this project, we will use MIRI + MRS and the NIRSpec IFU to map the environments of approximately three high mass protostellar objects (HMPOs) to reveal the spatially resolved structure and physics associated with the mass accretion and outflow processes. The goal is not only to get good S/N on continuum flux associated with the high mass protostars, but also understand gas and solid-state absorption features in the spectra that trace environmental chemistry and map spatially extended emission line species that reveal the disk and outflow properties. Additionally, observations of main sequence O/B stars show that they rarely (never) form in isolation. We will study the clustering properties of HMPO environments at this extremely young evolutionary state.

NOMINAL ALLOCATION (hours):

100

OBSERVING TEMPLATES:

OBSERVATION DETAILS:

Spectroscopy: Each HMPO and the 10-20'' region around it will be mapped with the MIRI MRS IFU mode (all three grating settings, whenever possible) and the NIRSpec IFU (Bands II and III) using the intra-visit IFU mosaics. The spatial mapping region depends on the geometry of the system, and because some areas have extremely high flux - especially at the long wavelength MIRI range at 20 μm and greater - some MIRI MRS IFU ''tile positions'' may need to have different readout parameters than other tiles in the IFU mosaic (some may need ''turned off''). Each MIRI tile position will execute the 4-point intra-tile dither pattern. NIRSpec IFU observations will also execute a comparable intra-tile dither.

This is an IFU mapping program, so to decrease mechanism movements and optimize overheads, it is likely most efficient to execute a full dither pattern at each grating setting prior to moving the grating (20s dither overheads/offset vs. ~60s). Some regions in the HMPO environments are extremely bright at 20 μm and long-ward (>10Jy). When possible, the bright nebular regions will be avoided in the IFU mapping. But the HMPOs can also be extremely bright in the longest wavelength MIRI channels and the long wave grating settings will saturate in some regions of an IFU mosaic. It would be optimal to execute all dither positions that will not saturate the detector with all gratings first, and then return to the dither positions that will likely saturate towards the end of the target visit. The saturation will be worst in the long wavelength channel with MIRI, so perhaps the longest grating setting should be executed last for each target, to limit persistence effects.

Slew overheads could be minimized if MIRI observations and NIRSpec observations are consecutive.

The embedded high mass stars all have luminous IR nebula nearby or associated with them (surface brightness of 5 Jy/arcsec or higher). Hence, detailed MIRI imaging of these regions will likely prove unfeasible. This makes the IFU mapping the main means to reveal the detailed environments of the HMPOs.

CONSTRAINTS:

Some IFU mosaic tile positions may need different readout patterns and/or exposure times. Ordering of dithered exposure positions may be needed to mitigate persistence effects in this program and subsequent observations.

PARALLEL Observations possible (yes/no/pure parallel)?

Because of the IFU mapping nature of this observation, it needs to be executed as prime science. It might be possible/desirable to execute some MIRI MRS program background exposures while NIRSpec IFU is integrating on the targets (perhaps also to flush persistence from the MRS detectors, post-observing if MIRI is executed first). Taking pure parallel NIRCam imaging might be useful for galactic stellar populations work.

PROGRAM COORDINATOR/DATE: Tracy Beck/ 5 Dec 2011

For more information about this program refer to the latest version of the SODRM.

TITLE: IFU Survey of Resolved Young Stellar Objects

ID: 93110

GOAL:

Spatially-resolved observations of young stellar objects (YSOs) are critically important for understanding star formation and early stellar evolution. Constraints on the spatial distribution of line and dust continuum emission reveal key details of mass loss in jets, the interaction between jets and infalling envelopes, and the chemical and kinematic structure of disks and envelopes. The NIRSpec and MIRI IFUs will enable spatially resolved observations of many nearby YSOs. This program outlines one possible study comprising a sample of known extended YSOs, including Class I protostars and proplyds in order to span a range of evolutionary states and birth environments. The proposed observations will measure mass outflow and accretion rates, the chemical and density structure of protostellar envelopes and proplyd photoionization fronts, and the luminosities, spectral types, and multiplicity of the central stars. Spectral diagnostics of interest include the shock emission features from jets (such as H2 and [FeII]), silicate and water ice features seen in absorption against background stars, dust continuum and silicate feature emission from disks, atomic gas emission from mass accretion, and photospheric absorption lines. Binary companions may be detected, along with the disk seen in the mm range. Key observational concerns are the background selection, saturation avoidance by bright spoiler stars in the field, and from the background nebular emission at long wavelengths. Samples consist of many resolved close-by protostars and their jets with a wide magnitude range (K~11-18 at 2 kpc), and circumstellar disks around protostars (proplyds).

NOMINAL ALLOCATION (hours):

100

TARGET(S):

• Protostars: a representative sample of 4 fields with 1 or 2 moderately extended protostars in each field, including L1527 IRS, L1634, L1157.
• Proplyds: 9 known objects close to the Trapezium in the Orion Nebula Cluster

OBSERVING TEMPLATES:

MIRI IFU
NIRSpec IFU

OBSERVATION DETAILS:

The protostars will be observed with the MIRI and NIRSpec IFUs using mosaics to cover at least a 10''x10'' region. For both instruments, all 3 grating settings are used whenever possible without saturating on the central source. This will produce full spectra at each point from 0.6- 28.3 μm.

CONSTRAINTS:

May want specific Position Angles for some sources?
May possibly get background measurements from the alternate instrument during parallels for this program.

COMMENTS:

Many of these observations could be taken with the same GS slew as cluster targets. We have grouped them together in the program under a single observation folder to indicate which we think could be done this way.

The pointing accuracy needed for the IFU mosaics would likely not not require a TA.

This program could be expanded to more targets. Many more protostars with resolvable jets and outflow cavities exist in the literature.

L1527 with overlays showing the MRS mosaic and individual pointings on several background stars.

Orion Proplyds near the Trapezium. Shown are positions for MRS and NIRSpec IFU observations. are positions for MRS and NIRSpec IFU observations.

PROGRAM COORDINATOR/DATE: James Muzerolle/Diane Karakla/Feb 13, 2012

For more information about this program refer to the latest version of the SODRM.

TITLE: High resolution imaging-spectroscopy of gas in protoplanetary disks

ID: 93115

GOAL: This program aims at obtaining high fidelity, high S/N (>200) NIRSpec+MIRI IFU spectroscopy of gas in a significant sample of protoplanetary disks. The key objectives are to

1. obtain high quality spectra of the central point source (and any companions) and
2. search for extended line emission on 0.2-1.0 arcsecond scales.

NOMINAL ALLOCATION (hours):

100 hours

TARGET(S):

59 bright (0.05-0.5 Jy) and nearby (Perseus, Taurus, Oph, Lupus) protoplanetary disks spanning a range of evolutionary stages from the classical T Tauri stage up to the transitional stage. All are known to harbor large reservoirs of molecular gas, from ground-based IR CO surveys (e.g., Salyk et al. 2011). About half have detected water and OH gas with Spitzer (Pontoppidan et al. 2010).

OBSERVING TEMPLATE:

NIRSpec IFU spectroscopy
MIRI MRS

OBSERVATION DETAILS:

The program requires that the IFU image reconstruction and the CR corrections are optimized with a sufficient number of dithers. IFU dithers are not fully defined yet, so the time estimate assumes 5 point NIRSpec dithers and 5 point MIRI dithers. The integration times are adjusted to, on average yield S/N ratios >200 on the point source, while also maintaining high sensitivity to faint extended line emission from larger spatial scales in the disk, and in order to detect any contaminating jet emission. The program will also include a search for many weak lines on top of the bright disk continuum (including the rare isotopologues of water H₂¹⁸O i and H₂¹⁷O). This drives the observing strategy towards obtaining the highest possible S/N, ideally as high as S/N~500-1000. Most targets are bright, and will reach full detector wells at about 3-4 frames at about S/N~200 per full well. NIRSpec will obtain 5 ints x 5 dithers=25 full well ramps and MIRI 8 ints x 5 dithers = 32 full ramps, for a theoretical S/N of 1000. Of course, actual detector performance and other considerations with likely limit this estimate, but a S/N~500 should be a realistic goal (based on Spitzer experience).

The spectral setups will cover a contiguous span of 3-28  μm using one NIRSpec setup and all of the available MIRI MRS on using one NIRSpec setup and all of the available MIRI MRS setups:

• NIRSpec setups: F290/G395H
• MIRI setup: MRS - bands I, II and III

Using the NIRSpec and MIRI overhead spreadsheets, a total time per target of 4080s for NIRSpec and 6100s for MIRI. It is assumed that a separate target slew is required for each instrument.

CONSTRAINTS:

There are no additional scheduling constraints.

PARALLEL Observations possible (yes/no/pure parallel)?

This program does not have obvious potential for parallel observations.

COMMENTS:

Given the many bright targets and short exposure times, this is a very inefficient program. The total time required be significantly decreased by scheduling the NIRSpec and MIRI observations concurrently for each target, thus eliminating one target slew. Also, the targets are highly clustered with median shortest angular separations of 10s of arcminutes to 1 degree, potentially mitigating long telescope slews.

PROGRAM COORDINATOR/DATE: Klaus Pontoppidan/Feb 13, 2012

For more information about this program refer to the latest version of the SODRM.

TITLE: Ice Mapping in Molecular Clouds

ID: 93120

GOAL: Ices are commonly found in the cold molecular clouds that are collapsing in the process of star formation. They form a large reservoir of various metals and may contain, for example, up to 80% of the available carbon and oxygen in these systems. Ices play a central role in the chemistry and evolution of protostellar protostellar disks. The chemical processing often occurs on the mantles of dust grains and understanding these processes is required to explain the observed chemical evolution. Observations of ices in the lines of sight toward protostar regions has been an important goal of the Spitzer c2d Legacy program, as well as other investigations. Oberg et al (2011) give an excellent summary of the state of knowledge about ice evolution. Many species of ice have been investigated with Spitzer/IRS and supplemented with ISO and ground based observations (Pontoppidan 2006) in the spectral range 3-20 μm. Among these are H₂O (3.1, 6.0, 11.2 μm), CO (4.7 μm), CO₂ (4.3, 15.2 μm), CH₃OH (3.5, 9.7 μm), NH₃ (8.0 μm), CH₄ (7.7 μm), and XCN (4.6 μm). The Spitzer data, all at l > 5 μm, has a spectral resolving power of only R=100 (only the 15.2 μm CO2 band could be observed with R=600) and the analysis of these data requires complex decomposition techniques. We propose a small survey of ices in 12 molecular clouds using background stars to obtain absorption line spectra using the MIRI MRS and the NIRSpec MSA. This will allow us to produce preliminary maps of the fractional ice abundances as a function cloud density, temperature and the distance from embedded protostars. The improved resolving power and sensitivity will allow a much better analysis of the ice abundances relative to H₂O and constrain models of chemical evolution in these environments.

NOMINAL ALLOCATION (hours):

100

TARGET(S):

• LDN-328
• BHR78
• L438
• B59
• L1772
• B72
• DC300.2-03.5
• DC300.7-01.0
• L429C Mu 8
• L100
• DC346.6+07.8

OBSERVING TEMPLATE:

MIRI MRS
NIRSpec MSA

5 background stars will be observed with the MIRI MRS toward each cloud. Although most of the targets in each cluster are more than 20 arcsec apart, some are not.

For each background star we observe with all 3 MIRI MRS grating configurations. The scientific goals require a resolving power of only 500-1000 so we intend to bin the data by a factor of about 5. The exposure times were set to obtain S/N=50 per resel in the binned data for a 1 mJy background star. A 4-point dither is requested. This is followed by NIRSpec MSA observations using the medium and long wavelength gratings only; we are not requesting coverage from 1-1.7 μm. The MSA is large enough to cover all 5 targets simultaneously although we do request a 2-point dither (nslitlet=2) on each side of the wavegap. For the NIRSpec observations the total time is strongly driven by the overheads. It takes almost no additional time to obtain S/N=100 rather than S/N=50, so the exposure times were specified on this basis. Up to 50 additional background stars will be observed with the NIRSpec exposures, covering bands of H₂O, CO and CO₂, in addition to the 5 MIRI targets.

Obtaining NIRSpec MSA spectra during the long MIRI MRS observations would yield a nice dataset on additional sightlines in the clusters.

COMMENTS:

This program is a great example of one for which cluster targets would represent a huge improvement. Currently, a target slew is specified for each star in the cloud. This requires 6 such slews (1 for each of the 5 MIRI observations and 1 for the NIRSpec observation). This requires 3 hours for the out of a total of 8.2 hours for each cloud. Reducing this to 1 target slew would save 2.5 hours, or about 30% of the total time.

These observations will likely be followed by more intensive mapping of the best individual clouds. In these cases, cluster targets will be absolutely essential. Without this mechanism, the overheads will be so excessive that it will severely limit this kind of science investigation.

PROGRAM COORDINATORS/DATE: Scott Friedman, Klaus Pontoppidan/13 February 2012.

TITLE: IFU Mapping of PDRs / HI Filaments

ID: 93130

GOAL: Emission from aromatic hydrocarbons and low states of molecular hydrogen dominates the JWST-accessible IR spectra of of dense photodissociation regions (PDRs). These species are important diagnostics of the physical properties of gas and dust in intense UV radiation fields. Detailed physical conditions, the distribution of various tracers of PDR structure, comparison of resolved emission feature widths, gas density and temperature distribution, clumpiness of the clouds, the excitation wavelength of different aromatic features and the nature of their carrier, measurement of the penetration depth of the exciting photons, and elemental and molecular abundances can be studied with high resolution observations in the different wavelength regions provided by MIRI and NIRSpec IFU spectra and associated confirmation imagery.

The three PDRs included here, NGC 7023, NGC 2023, and IC 63, were mapped with Spitzer (cf., Fleming et al, 2010, ApJ, 725, 159), but with the JWST observations described here it is possible to obtain much higher spectral and spatial resolution observations for more detailed study of important portions of specific interesting filaments in these bright regions as well as in other fainter targets.

NOMINAL ALLOCATION (hours):

TARGET(S):

PDRs in NGC 7023, IC 63, and NGC 2023.

OBSERVING TEMPLATES:

MIRI MRS-IFU
NIRSpec IFU

OBSERVATION DETAILS:

Spectroscopy: Each PDR will be observed with the MIRI and NIRSpec IFUs to cover a 3''x10'' region (requires 1x3 MIRI and 1x4 NIRSpec mini-map/mosaic with four-point dithering for excellent spatial sampling and NIRSpec spectrum gap coverage). For MIRI, all 3 grating settings will be taken. For NIRSpec, two grating settings are needed to cover the 3.3 μm aromatic feature as well as obtain good diagnostic atomic/molecular emission lines (G395H/F290LP & G235H/F170P). This produces full spectra at each point from 1.7-28.3 µm.

Imaging: Confirmation imaging with MIRI and possibly NIRSpec to facilitate alignment of the IFU maps would be beneficial, but it is not clear at this point how to specify this.

We will observe four filaments in each of three targets (NGC 7023, NGC 2023, and IC 63). Each filament will be observed at four separate locations (pointings labeled A through D) along the filament. The observations of the four pointings in each filament are grouped within an observation on the presumption that all four observations can be accomplished with only a single target slew. We also provided conservative estimates of the reduced durations to be expected on the assumption that two slews would be required for each filament.

At each pointing separate 10x3 arcsec "mini-maps" of size 1x3 for MIRI IFU and 1x4 for NIRSpec IFU will be obtained. Each mini-map sequence will consist of four dithered exposures at each tile of the map using G235H and G395H for NIRSpec and all MIRI spectral elements.

Our observing strategy yields for the mosaic at each pointing 16 separate NIRSpec exposures for each of the two NIRSpec gratings used and 12 separate exposures for each of the three MIRI gratings or a total of 128 NIRSpec exposures and 144 MIRI exposures per filament.

PARALLEL Observations possible (yes/no/pure parallel)?

Parallel NIRCam/MIRI imaging to the MIRI/NIRSpec IFU observations could be useful.

COMMENTS:

This program is loosely based upon a 2010 presentation by Gordon to the MIRI Science Team at Ringberg Castle.

This program could easily be expanded to more filaments of the included targets as well as a variety of other targets such as moderately extended planetary nebulae, regions in the galactic center, Orion, and the nuclei of starburst galaxies to name a few.

PROGRAM COORDINTOR/DATE: Tony Keyes, Tracy Beck, Karl Gordon/ Feb 2, 2012

For more information about this program refer to the latest version of the SODRM.

TITLE: Energy Feedback into Star Forming Clouds

ID: 93140

GOAL: In regions of low mass star formation, outflows in the form of jets and winds from young stars provide the most important mechanism for feedback of energy into the star forming clouds. Winds and jets from young stars are believed to power the cloud turbulence, help to regulate the star forming efficiency (SFE) and even disrupt and help to disperse parent cloud material and the extended envelopes of young stars. Yet, the dynamics of this process remain unclear. Snapshot imaging and spectroscopy can reveal the morphology and dynamics of a young star outflow, and comparison with shock excitation models place constraints on shock velocities and pre-shock densities. This allows for estimation of the effects of outflow feedback into the star forming clouds. Yet, more accurate information can also be derived from observations that reveal the full 3-D kinematic structure in the outflow through proper motion monitoring. Multi-cycle observations of young star jets from the Hubble Space Telescope have revealed that the temporal evolution of outflows is important to understand the full dynamical impact of turbulent energy feedback into the parent clouds. At the distance of Orion (~400pc), knots in young star jets have proper motions of up to ~0.''1 per year. In this program, we describe observations with NIRSpec MSA and IFU that will measure and study the full 3-D velocity and density profiles in Herbig-Haro (HH) jets from young stars, to quantify the turbulence and its effect on star formation. MSA observations will be executed on two outflows which have broad spatial extents (>2''), and two highly collimated jets will be observed with the IFU where the 3'' field of view is well matched to the 1.5-2'' jet widths. Observations will be acquired in the R~3000 (high resolution) setting in NIRSpec Band I, II and III for full coverage of the 1-5mm spectral region. Target emission lines of interest include numerous shock-excited H₂ lines in this spectral region, and forbidden atomic emission species such as [Fe II]. Observations of four jets will be acquired and repeated one to two times (two to three observations in total) over the course of 2 observing cycles with JWST.

NOMINAL ALLOCATION (hours):

100

TARGET(S):

Potential targets for NIRSpec MSA / IFU observations of young star outflows to probe energy feedback into star forming clouds:

• HH 211
• HH 111
• HH110
• HH 34

OBSERVING TEMPLATES:

NIRSpec MSA
NIRSpec IFU

• MSA Observations of HH 211 and HH 110:

  NIRSpec observations in the Band I, II and III grating settings will be obtained for full spectral coverage at R~3000 from 1-5mm. MSA configurations will be created for optimal placement of knots, & dithered through 4 positions for each /outflow MSA configuration (ie., targets are dithered behind a fixed MSA config to build up spatial sampling of the HH knots). The detector gap will be dithered to recover missing wavelengths (ndither= 3-4 positions at two MSA configurations). Overheads are derived assuming gratings are iterated before MSA configurations are changed. Estimate is that 3 different target sets (6 SA configurations) are needed to get full coverage of HH jet knots. Individual exposure times are on the order of 100s (3 integrations so not to saturate on brightest lines). Observations will be repeated to derive 3-D kinematic structure in the outflow.

• IFU Observations of HH 34 and HH 111:

  NIRSpec observations in the Band I, II and III grating settings will be obtained for full spectral coverage at R~3000 from 1-5mm. The IFU field will be dithered along the jet axis in a 1x~10 field mosaic. Individual exposure times are on the order of 100s per exposure (using 3 integrations to not to saturate on brightest lines), with a 4pt dither pattern at each IFU mosaic position. For sensitivity comparison to verify requested exposure times, Subaru 8m Telescope IR spectral observations of HH 34 were reported by Takami et al. (2006) at 1200s and 1400s the H and K infrared bands, respectively. Scaling for PSF size differences and IR sky backgrounds from the ground, we estimate that our requested NIRSpec exposures will be more sensitive. Observations will be repeated two times to derive 3- D kinematic structure in the outflow (total number of observations = 3 per target).

CONSTRAINTS:

MSA observations of HH 211 and HH 110 will require pre-imaging with NIRCam, and so full spectroscopy definition of these observations with the MSA will only come after pre-imaging is observed.

IFU Observations of HH 111 and HH 34 do not require pre-imaging, and assume that ''coarse accuracy TA'' using positions for reference star positions is available. Once IFU observations are started at a given telescope orient, the repeat observations should be executed at a similar orientation for proper reference of proper motions.

PARALLEL Observations possible (yes/no/pure parallel)?

This program needs to be executed as prime science because of the specific dither pattern requested (matched to HH target geometries). Parallel observations w/ NIRCam or MIRI could be possible, but might not be so useful on ''blank'' sky in these star forming regions.

PROGRAM COORDINATORS/DATE: Tracy Beck,Diane Karakla/9 Jan 2012

For more information about this program refer to the latest version of the SODRM.

TITLE: Galactic Center Monitoring

ID: 93150

GOAL: This program will study the kinematics and chemistry of stellar populations near the Galactic center. NIRCam imaging imaging at two epochs will provide proper motions for a very large number of stars. NIRSpec MSA spectroscopy will yield radial velocities with 10 km/s precision and chemical abundances for 1000 bright (9 < K < 13) giants with prominent spectral features in the 1.7-3.0 µm spectral region. The ultimate goal is to understand how the central cluster formed and whether it is a transient phenomenon indicative of a recent cluster-merger event or whether it is more of a steady-state phenomenon that regularly ingests small clusters to maintain a mix of old and young stars. If young stars all share certain phase-space parameters, this will lend credence to the first interpretation.

NOMINAL ALLOCATION (hours):

TARGET(S):

Imaging of a 10' x 10' region centered on the Galactic center.

Spectroscopy of 1000 bright giants in 5 separate fields contained in this larger imaging region.

OBSERVING TEMPLATES:

NIRCam Imaging
NIRSpec MSA Spectroscopy

OBSERVATION DETAILS (NIRCam):

The observations will be done in three phases. The first two phases will be done during the first year of operations, and the last phase will be done three to four years later, to maximize the baseline for the proper motions.

The NIRCam imaging will cover the inner 10' x 10' of the central cluster, taken with a 2x4 mosaic tile. At each tile in the mosaic, we will take a 6-point full-field dither with 2 secondary dithers at each primary location for a total of 12-pointings per tile. We will construct the mosaic in the SWC and LWC simultaneously using a narrow-band pair of filters (F187N+F405N) and a medium-band pair of filters (F182M+F410M). The narrow-band images will be 100s total and the medium-band images will be 200s total.

OBSERVATION DETAILS (NIRSpec):

The NIRSpec spectroscopy will cover 5 fields of view contained in the 10'x10' imaging region. Each field of view contains 1-3 target sets for a total of 10 target sets. Each target set contains about 100 targets for a total of 1000 targets. The MSA must be configured during NIRSpec target acquisition to block light from bright targets and minimize persistence in the detector.

The MSA will be configured with slitlets that are 1 shutter wide along the dispersion axis and 2 shutters tall along the spatial axis to measure background while minimizing contamination in this crowed region. Sources will be placed first in the bottom shutter of each slitlet and then nodded to the top shutter. The MSA will then be reconfigured to shift every slitlet by one shutter along the dispersion axis. Sources will be placed first in the top shutter and then the bottom shutter of the new slitlet. In total, each source will be observed in four times in two slitlets.

NIRSpec exposure times will be short (0.5-11 minutes) because the stars are very bright (9 < K < 13). The NRSRAPID readout pattern (NFRAME=1) is used when the NRS readout pattern (NFRAME=4) would yield fewer than 6 groups. Targets in FIELD-C3 are so bright that only 3 groups are possible before saturation, so we obtain 3 integrations to facilitate cosmic ray identification and correction.

An MSA confirmation image will be obtained for the 6 fainter target sets that do not saturate in two groups. The MSACONF image will be used to improve radial velocity accuracy. The remaining 4 target sets are too bright for a confirmation image.

About 1 hour of spacecraft time will be spent on each field. Dithers within each field will be less than 1 arcsec, even when when switching between target sets. Thus, only 1 NIRSpec target acquisition is needed for each field of view. Ideally, each field of view should be one visit with one FGS guide star acquisition and one NIRSpec target acquisition. All the NIRSpec observations should form a single observation with one large slew and four medium angle offsets.

CONSTRAINTS:

The NIRSpec MSA observations must be at least 2 months (TBC) after the NIRCam imaging to allow time for the observer to select targets and specify MSA configurations.

It might be interesting to take some MIRI observations in parallel with the NIRCam observations, if that is possible. It will give us some kind of probe into the mid-IR populations in the vicinity of the galactic center. The NIRCam mosaic will be large enough that if MIRI is observed in parallel in all observations, then we will get some MIRI-NIRCam overlap.

The NIRSpec observations will observe at 4 dither locations, so pure parallel imaging might be useful.

COMMENTS:

This is a program combines two observing scenarios, one authored by Jeff Valenti and one authored by Jay Anderson.

PROGRAM COORDINATORS/DATE: Jay Anderson, Jeff Valenti/December 16, 2011

For more information about this program refer to the latest version of the SODRM.

TITLE: The JWST Globular Cluster Survey

ID: 93180

GOAL: NIRCam imaging of a large population of Milky Way globular clusters will be used to establish the infrared color to establish the infrared color magnitude diagram and calibrate its dependency on metallicity. Infrared imaging offers the opportunity to measure the complete stellar populations of each cluster, from the brightest giants to the coolest dwarfs, and will reveal features in the color magnitude diagram that can be modeled to derive fundamental parameters for each system (e.g., accurate ages and distances). The stellar mass function will be measured down to the hydrogen-burning limit and its dependency on dynamics can be studied by exploring population trends.

The F090W and F277W filters can be observed simultaneously for this study, and a single JWST field of view will yield enough stars. The location of the field can be set to directly overlap the existing HST ACS survey of clusters to provide panchromatic wavelength coverage. The exposure depth will need to reach 0.5 mag below the bottom of the main-sequence with a S/N ~ 10. For a 12 Gyr population, a 0.08 Msun metal-poor star has J = 11 according to the Dartmouth Stellar Evolution models. According to the JWST ETC, for clusters at ~10 kpc, the exposure times will be 1 hour in F090W and 0.5 hours in F277W (based on an M5V star). At ~20 kpc (the furthest clusters in the survey), the exposure times will be 5 hours in F090W and 3 hours in F277W. The table below summarizes these approximate constraints for clusters with d < 5 kpc, d < 10 kpc, d < 15 kpc, and d < 20 kpc.

NOMINAL ALLOCATION (hours):

TARGET(S):

OBSERVING TEMPLATE:

CONSTRAINTS:

The fields should overlap the previous ACS imaging from the HST Treasury Survey as much as possible. Given the field of view, this should not impose strict constraints on the roll angle.

NIRISS parallel imaging would provide additional field coverage in the periphery of each cluster. This imaging would be useful to explore stellar population gradients and to constrain dynamical models of clusters (e.g., mass segregation).

PROGRAM COORDINATOR/DATE: Jason Kalirai/5 Jan 2012

For more information about this program refer to the latest version of the SODRM.

TITLE: HST Legacy Astrometry

ID: 93190

GOAL: When globular clusters formed, gas clouds condensed into objects with a variety of masses. Objects with more than about 0.08M☉ of mass were able to ignite hydrogen as they collapsed, and these low-mass stars continue to shine with about a thousandth of the sun's luminosity. Objects less massive than this were not able to ignite hydrogen and thus could not generate their own heat; these brown dwarfs were doomed to die a slow, cold death. Although these brown dwarfs start off with about the luminosity of their slightly more massive stellar brothers, after about 10 Gyrs, these 0.07 M☉ brown dwarfs have about five millionths of the sun's luminosity and a temperature of about 1000 K. Since globular clusters are about 12.5 Gyrs old, there should be a sharp contrast between the stars that could ignite hydrogen and those that are just fading away.

When we use HST to look for faint main-sequence stars in globular clusters, we do not see a sharp end to the main sequence, which would be indicative of the hydrogen-burning limit (HBL). Rather, we see a gradual tapering of the luminosity function, indicating that the stars are getting fainter and their photons redder than HST can observe. By going to the IR, we will be able to see the stars that have faded redward of HST's sensitivity. Our goal in this program is to use NIRCam to image the deep fields in M4, NGC 6397, 47 Tuc, and Omega Centauri that have already been observed by HST so that we that we can complement HST's visible images with IR images. A sub-HBL star with about 0.07 M☉ will receive about 1000 photons in a 1000s F150W NIRCam exposure, and will receive even more flux more through the redder filters. We should be able to detect brown dwarfs down to about 0.05 M☉ in the reddest filters, assuming the background from the halos of the brightest giants is not pathological. This will give us new information about the cooling properties of low-mass objects, and the formation details of the clusters themselves.

The overall plan will be to take this set of observations early in JWST's lifetime, then to repeat the observations near the end of JWST's lifetime, so that we can get PM-membership information for the faint stars.

NOMINAL ALLOCATION (hours):

TARGET(S):

OBSERVING TEMPLATES:

OBSERVATION DETAILS:

Imaging: We will center one of the NIRCam modules on a field that HST has previously observed deeply. This will be a field at an intermediate radius where there are plenty of stars, but the crowding is not bad. We will dither only to cover the SCA gaps. The other module will take a similar set of data on a field that does not have previous observations.

It might be worthwhile to take some MIRI observations, if we can observe at an orientation where MIRI will be imaging a field at a larger cluster radius, so that crowding will not be an issue for MIRI. We may even want to make sure there are no particularly bright stars in MIRI'ss field of view.

It might be interesting to take spectra with NIRSpec of the parallel fields. The star fields in the vicinity of these deep fields should be relatively well mapped from the ground such that we can get good positions to know which MSA slits to open.

COMMENTS:

This program is a follow-on program to several HST prorams that Harvey Richer has been PI of. Some of the observations may overlap with Jason Kalirai's WD JWST program but it is likely that our focus on faint red things may make for an optimal observing strategy for WDs.

POGRAM COORDINATOR/DATE: ay Anderson/December 8, 2011

For more information about this program refer to the latest version of the SODRM.

TITLE: White Dwarf Cooling Ages of Globular Clusters

ID: 93200

GOAL: NIRCam imaging of the nearest 11 globular clusters will be used to uncover the remnant population of white dwarfs in each system. The white dwarf cooling sequences will be measured using two-filter photometry down to the truncation point. The luminosity and color function of these white dwarfs provides an excellent, and main-sequence turnoff independent, age diagnostic for each cluster. The cooling sequences from this study will also motivate new tests to white dwarf models in the near IR, where collisionally induced absorption of H₂ (seen in the visible) is expected to be important. HST has successfully performed these studies in the three nearest globular clusters at optical wavelengths. Only JWST can extend the study to additional clusters.

Although young white dwarfs are hot, the stars near the bottom of the cooling sequence in old stellar populations have Teff = 4000 K. These stars are quite red, and can be imaged efficiently with JWST/NIRCam's bluer filters. The F090W filter has much better overall throughput than the bluer F070W filter, and the F150W filter is strongly preferred over the F115W (short wavelength baseline with F090W) and F200W (too red for white dwarfs) filters. The location of each field will be carefully chosen to ensure that a statistically significant number of white dwarfs are in the field of view, while now compromising photometric accuracy because of crowding. The dual channel of NIRCam can be used to obtain simultaneous imaging with F277W during both the F090W and F150W observations. These redder data will provide valuable characterization of the stellar main sequence in each cluster, and also be sensitive to accretion disks or planets around the brighter white dwarfs (e.g., through spectral energy modeling).

Based on previous HST experience and white dwarf models from B. Hansen, the truncation point of the white dwarf cooling sequence in a 12 Gyr population occurs at M_F814W = 15.2. The exposure time for each cluster is set to achieve a S/N = 10 measurement of this limit in both F090W and F150W. The F277W depth is not constrained. The limiting magnitude is set after factoring in both the distance to each cluster and the extinction along the line of sight, as summarized in the Table below. The last two columns give the exposure time in hours for each cluster, based on the JWST ETC. The three clusters previously observed on HST, M4, NGC 6397, and 47 Tuc are also included here. At <10% of the cost of the program, it would be beneficial to observe them in the same filters and set up as the new clusters to rule out systematic, wavelength-dependent errors in the models.

NOMINAL ALLOCATION (hours):

TARGET(S):

OBSERVING TEMPLATE:

PARALLEL Observations possible (yes/no/pure parallel)?

NIRISS parallel imaging would provide additional field coverage in the periphery of each cluster. The imaging would characterize both white dwarfs and main-sequence stars providing added leverage to study stellar and dynamical evolution processes.

PROGRAM COORDINTORS/DATE: Jason Kalirai, Brad Hansen, Harvey Richer,) Jay Anderson/ jam 5, 2012

For more information about this program refer to the latest version of the SODRM.

TITLE: NIRSpec Dense Field Spectroscopy of Omega Cen

ID: 93210

GOAL: Obtain radial velocities and chemical abundances for CNO from R=3000 spectra of > 5000 stars in Omega Cen. This globular cluster observation will also flex the capabilities of NIRSpec for operating in a very dense field of sources, with 1 source for every 5-10 shutters on the MSA.

NOMINAL ALLOCATION (hours):

TARGET(S):

Targets are drawn from Jay Anderson's ACS catalog of stars in the center of Omega Cen. They are main sequence and giant branch stars ranging from J ~ 12 - 20.

OBSERVING TEMPLATE:

OBSERVATION DETAILS:

Obtain R = 3000 NIRSpec spectra in all available bands (G140H, G235H, G395H). Use 43 MSA configurations to obtain spectra of 5896 stars in Field #2 from the observing scenario report.

No contemporaneous pre-imaging is necessary because there is high-quality astrometry available from HST/ACS.

CONSTRAINTS:

PARALLEL Observations possible (yes/no/pure parallel)?

PROGRAM COORDINATOR/DATE: Jason Tumlinson, November 21, 2011