This week on HST


HST Programs: December 5, 2011 - December 11, 2011


Program Number Principal Investigator Program Title
11539 James C. Green, University of Colorado at Boulder COS-GTO: Io's Atmospheric Response to Eclipse
12041 James C. Green, University of Colorado at Boulder COS-GTO: Io Atmosphere/STIS
12067 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12073 Julianne Dalcanton, University of Washington A Panchromatic Hubble Andromeda Treasury - I
12074 Julianne Dalcanton, University of Washington A Panchromatic Hubble Andromeda Treasury - I
12103 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12228 Glenn Schneider, University of Arizona Probing for Exoplanets Hiding in Dusty Debris Disks: Inner {<10 AU} Disk Imaging, Characterization, and Exploration
12284 James Muzerolle, Space Telescope Science Institute Light Echoes from a Periodic Protostellar Outburst
12320 Brian Chaboyer, Dartmouth College The Ages of Globular Clusters and the Population II Distance Scale
12440 Sandra M. Faber, University of California - Santa Cruz Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey -- GOODS-South Field, Non-SNe-Searched Visits
12448 Arlin Crotts, Columbia University in the City of New York Towards a Detailed Understanding of T Pyx, Its Outbursts and Shell
12468 Keith S. Noll, NASA Goddard Space Flight Center How Fast Did Neptune Migrate? A Search for Cold Red Resonant Binaries
12474 Boris T. Gaensicke, The University of Warwick The frequency and chemical composition of rocky planetary debris around young white dwarfs
12481 Carrie Bridge, California Institute of Technology WISE-Selected Lyman-alpha Blobs: An Extreme Dusty Population at High-z
12488 Mattia Negrello, Open University SNAPshot observations of gravitational lens systems discovered via wide-field Herschel imaging
12514 Karl Stapelfeldt, NASA Goddard Space Flight Center Imaging of Newly-identified Edge-on Protoplanetary Disks in Nearby Star-Forming Regions
12521 Xin Liu, Harvard University The Frequency and Demographics of Dual Active Galactic Nuclei
12550 Daniel Apai, University of Arizona Physics and Chemistry of Condensate Clouds across the L/T Transition - A SNAP Spectral Mapping Survey
12569 Sylvain Veilleux, University of Maryland Ionized and Neutral Outflows in the QUEST QSOs
12592 Ryan Foley, Smithsonian Institution Astrophysical Observatory Understanding the Progenitor Systems, Explosion Mechanisms, and Cosmological Utility of Type Ia Supernovae
12597 David Jewitt, University of California - Los Angeles Hubble Imaging of a Newly Discovered Main Belt Comet
12665 Mark R. Showalter, SETI Institute Orbital Evolution and Stability of the Inner Uranian Moons
12673 Howard E. Bond, Space Telescope Science Institute HST Observations of Astrophysically Important Visual Binaries
12713 Peter McCullough, Space Telescope Science Institute Spatial Scanned L-flat Validation Pathfinder

Selected highlights

GO 12073/74: A Panchromatic Hubble Andromeda Treasury


M31: the Andromeda spiral galaxy
M31, the Andromeda galaxy, is the nearest large spiral system to the Milky Way (d ~ 700 kpc), and, with the Milky Way, dominates the Local Group. The two galaxies are relatively similar, with M31 likely the larger system; thus, Andromeda provides the best opportunity for a comparative assessment of the structural properties of the Milky Way. Moreover, while M31 is (obviously) more distant, our external vantage point can provide crucial global information that complements the detailed data that we can acquire on individual members of the stellar populations of the Milky Way. With the advent on the ACS and, within the last 2 years, WFC3 on HST, it has become possible to resolve main sequence late-F and G dwarfs, permitting observations that extend to sub-solar masses in M31's halo and disk. Initially, most attention focused on the extended halo of M31 (eg the Cycle 15 program GO 10816 ), with deep imaging within a limited number of fields revealing the complex metallicity structure within that population. With the initiation of the present Multi-Cycle Treasury program, attention switches to the M31 disk. "PHAT" will conduct a multi-waveband survey of approximately one third of disk and bulge, focusing on the north-east quadrant. Observations will extend over the next three cycles, and will provide a thorough census of upper main-sequence stars and star forming regions, matching the stellar distribution against the dust and gas distribution.
GO 12284: Light echoes from a Periodic Protostar Outburst


The central regions of the young star cluster, IC 348
General indications are that the majority of stars in the Galactic disk form within clusters. Understanding both the cluster environment and the detailed structure of individual young stars is therefore important to understanding how most stars - and any associated planetary systems - form and evolve. The present program focuses on an unusual star within the young (2-5 million year) cluster IC 348. Lying at a distance of approximately 315 parsces within the constellation of Perseus, IC 348 is a cluster that includes several hunred stars. This particular program focuses on one of the brightest members of the cluster, the relatively faint and, hitherto, rather anonymous protostar LRLL 54361. Observations with Spitzer have revealed significant outbursts that lead to the obejct varying in luminosity by almost a factor of ten, and appear to recur with a periodicity of approximately 25 days. The present set of observations will use the WFC3-IR camera to probe the detailed structure in the vicinity of the protostar, both in broadband F160W (H-band) and the narrow-band F164N filter, which encompasses lines by Fe II.

GO 12468: How Fast Did Neptune Migrate? A Search for Cold Red Resonant Binaries


Preliminary orbital determination for the KBO WW31, based on C. Veillet's analysis of CFHT observations; the linked image shows the improved orbital derivation, following the addition of HST imaging
The Kuiper Belt consists of icy planetoids that orbit the Sun within a broad band stretching from Neptune's orbit (~30 AU) to distance sof ~50 AU from the Sun (see David Jewitt's Kuiper Belt page for details). Over 500 KBOs (or trans-Neptunian objects, TNOs) are currently known out of a population of perhaps 70,000 objects with diameters exceeding 100 km. Approximately 2% of the known TNOs are binary (including Pluto, one of the largest known TNOs, regardless of whether one considers it a planet or not). TNOs are grouped within three broad classes: resonant objects, whose orbits are in m,ean motion resonance with Neptune, indicating capture; scattered objects, whose current orbits have evolved through gravitational interactions with Neptune or other giant planets; and classical TNOs, which are on low eccentricity orbits beyond Neptune, with no orbital resonance with any giant planet. The latter clas are further sub-divided into "hot" and "cold" objects, depending on whether the orbits have high or low inclinations with respect to the ecliptic. Cold, classical TNOs show relatively uniform characteristcis, including red colours, high albedos and an extremely high binary fraction (>30%). They are believed to have formed in situ, and were therefore in place to experience the range of gravitational interactions as the giant planets migrated to their present location. As that migration occurred, subsets are expected to have been trapped in transitory resonance orbits. The present proposal aims to use HST to complete a photometric survey of all known resonant TNOs, with the goal of identifying the proportion of cold classical TNOs that have been captured. The relative number of such obejcts can be used to constrain models for Neptune's orbital migration in the early Solar System.

GO 12488: SNAPshot observations of gravitational lens systems discovered via wide-field Herschel imaging


ACS images of galaxy-galaxy Einstein ring lenses from the Sloan survey
Gravitational lensing is a consequence the theory of general relativity. Its importance as an astrophysical tool first became apparent with the realisation (in 1979) that the quasar pair Q0957+561 actually comprised two lensed images of the same background quasar. In the succeeding years, lensing has been used primarily to probe the mass distribution of galaxy clusters, using theoretical models to analyse the arcs and arclets that are produced by strong lensing of background galaxies, and the large-scale mass distribution, through analysis of weak lensing effects on galaxy morphologies. Gravitational lensing can also be used to investigate the mass distribution of individual galaxies. Until recently, the most common background sources that were being detected and investigates were quasars. Galaxy-galaxy lenses, however, offer a distinct advantage, since the background source is extended, and therefore imposes a stronger constraints on the mass distribution of the lensing galaxy than a point-source QSO. HST has carried out a number of programs following up candidate lenses identified from the Sloan Digital Sky Survey (eg GO 10886 , GO 11289 , GO 12210 ). The present program is using WFCE on HST to obtain follow-up near-infrared (F110W) images of up to 200 candidate lenses selected from the Herschel Astrophysical Terahertz Large Area (H-ATLAS) and the Herschel Multi-tiered Extra-galactic (HerMES) surveys. The HST data will verify the nature of those candidates, and provide the angular resolution necessary to model the mass distribution.

Past weeks:
page by Neill Reid, updated 8/12/2011