This week on HST


HST Programs: December 13, 2010 - December 19, 2010

Program Number Principal Investigator Program Title
11548 S. Thomas Megeath, University of Toledo NICMOS Imaging of Protostars in the Orion A Cloud: The Role of Environment in Star Formation
11591 Jean-Paul Kneib, Laboratoire d'Astrophysique de Marseille Are Low-Luminosity Galaxies Responsible for Cosmic Reionization?
11617 Matthew Holman, Smithsonian Institution Astrophysical Observatory HAT-P-1: A Direct Glimpse into the Atmosphere of a Hot Jupiter
11644 Michael E Brown, California Institute of Technology A dynamical-compositional survey of the Kuiper belt: a new window into the formation of the outer solar system
11721 Richard S. Ellis, California Institute of Technology Verifying the Utility of Type Ia Supernovae as Cosmological Probes: Evolution and Dispersion in the Ultraviolet Spectra
11840 Andrew J. Levan, The University of Warwick Identifying the host galaxies for optically dark gamma-ray bursts
12041 James C. Green, University of Colorado at Boulder COS-GTO: Io Atmosphere/STIS
12058 Julianne Dalcanton, University of Washington A Panchromatic Hubble Andromeda Treasury - I
12099 Adam Riess, The Johns Hopkins University Supernova Follow-up for MCT
12169 Boris T. Gaensicke, The University of Warwick The frequency and chemical composition of planetary debris discs around young white dwarfs
12184 Xiaohui Fan, University of Arizona A SNAP Survey for Gravitational Lenses Among z~6 Quasars
12201 Brian Siana, California Institute of Technology Ionizing Emission from the Faint Galaxies Responsible for Reionization
12209 Adam S. Bolton, University of Utah A Strong Lensing Measurement of the Evolution of Mass Structure in Giant Elliptical Galaxies
12210 Adam S. Bolton, University of Utah SLACS for the Masses: Extending Strong Lensing to Lower Masses and Smaller Radii
12212 D. Michael Crenshaw, Georgia State University Research Foundation What are the Locations and Kinematics of Mass Outflows in AGN?
12213 Roelof S. de Jong, Astrophysikalisches Institut Potsdam The Stellar Halo Profiles of Massive Disk Galaxies
12215 Nancy R. Evans, Smithsonian Institution Astrophysical Observatory Searching for the Missing Low-Mass Companions of Massive Stars
12228 Glenn Schneider, University of Arizona Probing for Exoplanets Hiding in Dusty Debris Disks: Inner {<10 AU} Disk Imaging, Characterization, and Exploration
12234 Wesley Fraser, California Institute of Technology Differentiation in the Kuiper belt: a search for silicates on icy bodies.
12264 Simon L. Morris, University of Durham The Relationship between Gas and Galaxies for 0
12272 Christy A. Tremonti, University of Wisconsin - Madison Testing Feedback: Morphologies of Extreme Post-starburst Galaxies
12278 Thomas R. Ayres, University of Colorado at Boulder Advanced Spectral Library Project: Cool Stars
12283 Matthew A. Malkan, University of California - Los Angeles WFC3 Infrared Spectroscopic Parallel Survey {WISP}: A Survey of Star Formation Across Cosmic Time
12284 James Muzerolle, Space Telescope Science Institute Light Echoes from a Periodic Protostellar Outburst
12289 J. Christopher Howk, University of Notre Dame A COS Snapshot Survey for z < 1.25 Lyman Limit Systems
12302 Edward F. Guinan, Villanova University Probing the Atmospheres of Cepheids with HST-COS: Pulsation Dependences, Plasma Dynamics and Heating Mechanisms
12307 Andrew J. Levan, The University of Warwick A public SNAPSHOT survey of gamma-ray burst host galaxies
12320 Brian Chaboyer, Dartmouth College The Ages of Globular Clusters and the Population II Distance Scale
12324 C. S. Kochanek, The Ohio State University The Temperature Profiles of Quasar Accretion Disks
12326 Keith S. Noll, Space Telescope Science Institute Hubble Heritage 2.0
12434 Andrei Lobanov, Max-Planck-Institut fur Radioastronomie Deciphering the Flare in the Crab Nebula:

Selected highlights

GO 11644: A dynamical-compositional survey of the Kuiper belt: a new window into the formation of the outer solar system

The view from Sedna: an artist's impression The Kuiper Belt lies beyond the orbit of Neptune, extending from ~30 AU to ~50 AU from the Sun, and includes at least 70,000 objects with diameters exceeding 100 km. Setting aside Pluto, the first trans-Neptunian objects were discovered in the early 1990s. Most are relatively modest in size, with diameters of a few hundred km and photometric properties that suggested an icy composition, similar to Pluto and its main satellite, Charon. Over the last three years, a handful of substantially larger bodies have been discovered, with diameters of more than 1000 km; one of the objects, 2003 UB313, is comparable in size to Pluto (2320 km.). At the same time, ground-based surveys, such as the Deep Ecliptic Survey, the Canada-France Ecliptic plane Survey and the Palomar Quest Survey, scanned the ecliptic for fainter, lower-mass objects, with the aim of using their properties to assess the likely chemical composition and dynamical history of the early Solar System. The present program will use Wide Field Camera 3 to push up to 2 magnitudes fainter than these ground-based studies, providing reliable estimates of compositions for a representative sample of KBOs.
GO 11721: Verifying the Utility of Type Ia Supernovae as Cosmological Probes: Evolution and Dispersion in the Ultraviolet Spectra

Recent supernova in M100 Supernovae are the most spectacular form of stellar obituary. In recent years, these celestial explosions have acquired even more significance through the use of Type Ia supernovae as distance indicators in mapping the `dark energy' acceleration term of cosmic expansion. However, while there are well-established models for the two main types of supernovae (runaway fusion on the surface of a white dwarf in a binary system for Type Ia, or detonation of the core in Type II), some uncertainties remain as to the uniformity of the events. Consequently, there is potential for systematic bias in the distance estimates. One of the questionmarks comes from spectroscopy of a number of supernovae at intermediate redshift (z~0.5) that appears to show a substantial dispersion in properties at UV wavelengths. The present program aims to probe this issue by using STIS to obtain UV spectra of nearby supernovae, and therefore examining the detailed behaviour in the local universe.

GO 12169: The frequency and chemical composition of planetary debris discs around young white dwarfs

Artist's impression of a comet spiralling in to the white dwarf variable, G29-38 During the 1980s, one of the techniques used to search for brown dwarfs was to obtain near-infrared photometry of white dwarf stars. Pioneered by Ron Probst (KPNO), the idea rests on the fact that while white dwarfs are hot (5,000 to 15,000K for the typcail targets0, they are also small (Earth-sized), so they have low luminosities; consequently, a low-mass companion should be detected as excess flux at near- and mid-infrared wavelengths. In 1988, Ben Zuckerman and Eric Becklin detected just this kind of excess around G29-38, a relatively hot DA white dwarf that also happens to lie on the WD instability strip. However, follow-up observations showed that the excess peaked at longer wavelengths than would be expected for a white dwarf; rather, G 29-38 is surrounded by a dusty disk. Given the orbital lifetimes, those dust particles must be regularly replenished, presumably from rocky remnants of a solar system. G 29-38 stood as a lone prototype for almost 2 decades, until a handful of other dusty white dwarfs were identified from Spitzer observations within the last couple of years.In subsequent years, a significant number of DA white dwarfs have been found to exhibit narrow metallic absorption lines in their spectra. Those lines are generally attributed to "pollution" of the white dwarf atmospheres. Given that the diffusion time for metals within the atmospheres is short (tens to hundreds of years), the only reasonable means of maintaining such lines in ~20% of the DA population is to envisage continuous accretion from a surrounding debris disk. The present program aims to address this question by using COS to obtain UV observations of young white dwarfs, probing correlations with progenitor mass and examining the detailed composition of the accreted materials.

GO 12210: SLACS for the Masses: Extending Strong Lensing to Lower Masses and Smaller Radii

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 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. The Sloan Digital Sky Survey is a powerful tool for identifying candidate galaxy-galaxy lenses, and has provided targets for HST imagiung programs in several previous cycles. The presentprogram is using HST-ACS imaging to survey a further 135 strong lens candidates. The HST data will verufy the nature of those candidates, and provide the angular resolution necessary to model the mass distribution.

Past weeks:
page by Neill Reid, updated 12/19/2010