This week on HST


HST Programs: February 20 - February 26, 2012


Program Number Principal Investigator Program Title
12023 James C. Green, University of Colorado at Boulder COS-GTO: Cold ISM
12192 James T. Lauroesch, University of Louisville Research Foundation, Inc. A SNAPSHOT Survey of Interstellar Absorption Lines
12307 Andrew J. Levan, The University of Warwick A public SNAPSHOT survey of gamma-ray burst host galaxies
12310 Goeran Oestlin, Stockholm University LARS - The Lyman Alpha Reference Sample
12440 Sandra M. Faber, University of California - Santa Cruz Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey -- GOODS-South Field, Non-SNe-Searched Visits
12446 Michael Shara, American Museum of Natural History Ionization and Light Echoes in the T Pyxidis Nebula
12448 Arlin Crotts, Columbia University in the City of New York Towards a Detailed Understanding of T Pyx, Its Outbursts and Shell
12453 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12461 Adam Riess, The Johns Hopkins University Supernova Follow-up for MCT
12468 Keith S. Noll, NASA Goddard Space Flight Center How Fast Did Neptune Migrate? A Search for Cold Red Resonant Binaries
12471 Dawn K. Erb, University of Wisconsin - Milwaukee The Bottom of the Iceberg: Faint z~2 Galaxies and the Enrichment of the IGM
12476 Kem Cook, Eureka Scientific Inc. Measuring the Hubble Flow Hubble Constant
12488 Mattia Negrello, Open University SNAPshot observations of gravitational lens systems discovered via wide-field Herschel imaging
12502 Andrew S. Fruchter, Space Telescope Science Institute From the Locations to the Origins of Short Gamma-Ray Bursts
12507 Adam L. Kraus, University of Hawaii The Formation and Fundamental Properties of Wide Planetary-Mass Companions
12512 Alycia J. Weinberger, Carnegie Institution of Washington Debris Disk Chemistry from Spatially Resolved Spectroscopy
12514 Karl Stapelfeldt, NASA Goddard Space Flight Center Imaging of Newly-identified Edge-on Protoplanetary Disks in Nearby Star-Forming Regions
12516 Francesco R. Ferraro, Universita di Bologna COSMIC-LAB: Double BSS sequences as signatures of the Core Collapse phenomenon in star clusters.
12539 Nils Bergvall, Uppsala Astronomical Observatory A novel approach to find Lyman continuum leaking galaxies at z~0.3 with COS
12541 David P. Bennett, University of Notre Dame Measuring the Exoplanet Mass Function Beyond the Snow-Line
12546 R. Brent Tully, University of Hawaii The Geometry and Kinematics of the Local Volume
12549 Thomas M. Brown, Space Telescope Science Institute The Formation History of the Ultra-Faint Dwarf Galaxies
12550 Daniel Apai, University of Arizona Physics and Chemistry of Condensate Clouds across the L/T Transition - A SNAP Spectral Mapping Survey
12563 Trent J. Dupuy, Smithsonian Institution Astrophysical Observatory Very Low-Mass Pleiades Binaries
12568 Matthew A. Malkan, University of California - Los Angeles WFC3 Infrared Spectroscopic Parallel Survey WISP: A Survey of Star Formation Across Cosmic Time
12585 Sara Michelle Petty, University of California - Los Angeles Unveiling the Physical Structures of the Most Luminous IR Galaxies Discovered by WISE at z>1.6
12600 Reginald J. Dufour, Rice University Carbon and Nitrogen Enrichment Patterns in Planetary Nebulae
12603 Timothy M. Heckman, The Johns Hopkins University Understanding the Gas Cycle in Galaxies: Probing the Circumgalactic Medium
12610 Stephen T. Ridgway, National Optical Astronomy Observatory, AURA Convection and mass loss through the chromosphere of Betelgeuse
12616 Linhua Jiang, Arizona State University Near-IR Imaging of the Most Distant Spectroscopically-Confirmed Galaxies in the Subaru Deep Field
12684 Bruce McCollum, Jet Propulsion Laboratory Mapping the Physical Characteristics of the Pre-Merger Ejecta from the First Confirmed Stellar Merger
12713 Peter McCullough, Space Telescope Science Institute Spatial Scanned L-flat Validation Pathfinder

Selected highlights

GO 12307: A public SNAPSHOT survey of gamma-ray burst host galaxies


Artist's impression of a gamma-ray burst
Gamma ray bursts are events that tap extraordinary energies (1045 to 1047 joules) in remarkably short periods of time. Several thousands bursts have been detected over the last 30+ years, and analyses indicate that they can be divided into two classes with durations longer or shorter than 2 seconds. The short bursts appear to release more high energy radiation, so the two subsets are known as long/soft and short/hard bursts.The short/hard bursts appear to arise from coalescing binary systems (probably pairs of neutron stars or black holes), but the long/soft bursts appear to originate in the collapse of very massive stars. The latter sources are therefore almost certainly associated with star formation, so they act as signposts to active star-forming regions in the high redshift universe. Many of these bursts are sufficiently bright that ground-based spectroscopic observations allow reliable measurement of the redshift. In many cases, ground-based observations at later epochs are insufficient to detect the underlying host galaxy, and characterise its properties. This SNAPSHOT program uses the WFC3-IR camera to image the host galaxies of Swift-selected GRBs at redshifts less than 3. The data will permit statical analyses of the luminosities and morphologies of those systems.

GO 12448: Towards a Detailed Understanding of T Pyx, Its Outbursts and Shell


Artist's impression of the recurrent nova, RS Oph (by David Hardy)
Recurrent novae are generally agreed to be close binary systems, comprising a white dwarf and a companion main sequence star that is overflowing its Roche lobe, leading to period transfers of mass onto the white dwarf surface. The mass transfer episode triggers nuclear ractions, which lead the star increasing significantly in it luminosity. T Pyxidis is one such system, and it exhibited fairly regular outbursts every 20 years between its discovery, in 1890, and 1966. Since then, however, it has been dormant, a prolonged period of quiescence that led to suggestions, earlier this year, that it might either be headed for hibernation, or in the process of accumulating sufficient mass to trigger a type Ia supernova explosion (in about 1 million years). Perhaps prompted by these suggestions (a la Monty Python Mary Queen of Scots radio sketch), T Pyxidis erupted into activity on or around April 15th. The present HST observations are part of a time series designed to obtain multi-wavelength narrowband images of the illuminated ejecta.
GO 12453: Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos


The cluster MACS J1206.2-0.47, imaged by HST as part of the CLASH program
The overwhelming majority of galaxies in the universe are found in clusters. As such, these systems offer an important means of tracing the development of large-scale structure through the history of the universe. Moreover, as intense concentrations of mass, galaxy clusters provide highly efficient gravitational lenses, capable of concentrating and magnifying light from background high redshift galaxies to allow detailed spectropic investigations of star formation in the early universe. Hubble imaging has already revealed lensed arcs and detailed sub-structure within a handful of rich clusters. At the same time, the lensing characteristics provide information on the mass distribution within the lensing cluster. The present program aims to capitalise fully on HST's imaging capabilities, utilising the refurbished Advanced Camera for Surveys and the newly-installed Wide-Field Camera 3 to obtain 17-colour imaging of 25 rich clusters. The data will be use to map the mass profiles of the clusters and probe the characteristics of the high-redshift lensed galaxies. Since ACS and WFC3 can be operated in parallel, the program will also use parallel imaging in offset fields to search for high-redshift supernovae. The present observations target the cluster MACS 1115+0129 at z=0.35.

GO 12512: Debris Disk Chemistry from Spatially Resolved Spectroscopy


HST image of the debris disk around two nearby A stars, including HR 4796, one of the stars targeted by this program
Planet formation occurs in circumstellar disks around young stars. Most of the gaseous content of those disks dissipates in less than 10 million years, leaving dusty debris disks that are detectable through reflect light at near-infrared and, to a lesser extent, optical wavelengths. The structure of those disks is affected by massive bodies (i.e. planets and asteroids), which, through dynamical interactions and resonances, can produce rings and asymmetries. Analysis of the rangle of morphological structure in these systems provides insight into the distribution of properties of planetary systems. HST currently provides the most effective (in some cases, the only) means of achieving the high-contrast required for the detection of scattered light from these disks in the presence of the bright parent stars, and a number of HST post-SM4 programs are being devoted to obtaining high-resolution images for newly discovered systems (eg GO 12228, 12291, 12573, 12576). The present program takes a different tack, aiming to obtain spectroscopic imaging of disks around three bright nearby stars. The aim is to use the Space Telescope Imaging Spectrograph in coronagraphic mode, where an occulting bar is placed over the central star. The observations will be made with the G430L and G750L low-resoltuion gratings, covering the near-UV, optical and far-red regions of the spectrum. The resulting spectra will provide insight on the composition of the dust grains in these relatively young systems.

Past weeks:
page by Neill Reid, updated 26/1/2012