This week on HST


HST Programs: June 7, 2010 - June 13, 2010


Program Number Principal Investigator Program Title
11495 Carole A. Haswell, Open University The first direct detection of an extrasolar planetary stratosphere?
11520 James C. Green, University of Colorado at Boulder COS-GTO: QSO Absorbers, Galaxies and Large-scale Structures in the Local Universe.
11556 Marc W. Buie, Southwest Research Institute Investigations of the Pluto System
11557 Gabriela Canalizo, University of California - Riverside The Nature of low-ionization BAL QSOs
11565 Sebastien Lepine, American Museum of Natural History A search for astrometric companions to very low-mass, Population II stars
11567 Charles R. Proffitt, Computer Sciences Corporation Boron Abundances in Rapidly Rotating Early-B Stars.
11568 Seth Redfield, Wesleyan University A SNAPSHOT Survey of the Local Interstellar Medium: New NUV Observations of Stars with Archived FUV Observations
11592 Nicolas Lehner, University of Notre Dame Testing the Origin{s} of the Highly Ionized High-Velocity Clouds: A Survey of Galactic Halo Stars at z>3 kpc
11594 John M. O'Meara, Saint Michaels College A WFC3 Grism Survey for Lyman limit absorption at z=2
11595 John M. O'Meara, Saint Michaels College Turning out the Light: A WFC3 Program to Image z>2 Damped Lyman Alpha Systems
11598 Jason Tumlinson, Space Telescope Science Institute How Galaxies Acquire their Gas: A Map of Multiphase Accretion and Feedback in Gaseous Galaxy Halos
11603 Jennifer Andrews, Louisiana State University and A & M College A Comprehensive Study of Dust Formation in Type II Supernovae with HST, Spitzer and Gemini
11613 Roelof S. de Jong, Astrophysikalisches Institut Potsdam GHOSTS: Stellar Outskirts of Massive Spiral Galaxies
11635 Michael Shara, American Museum of Natural History In Search of SNIb/Ic Wolf-Rayet Progenitors and Comparison with Red Supergiants {SNII Progenitors} in the Giant ScI Spiral M101
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
11663 Mark Brodwin, Smithsonian Institution Astrophysical Observatory Formation and Evolution of Massive Galaxies in the Richest Environments at 1.5 < z < 2.0
11666 Adam J. Burgasser, University of California - San Diego Chilly Pairs: A Search for the Latest-type Brown Dwarf Binaries and the Prototype Y Dwarf
11669 Andrew S. Fruchter, Space Telescope Science Institute The Origins of Short Gamma-Ray Bursts
11670 Peter Garnavich, University of Notre Dame The Host Environments of Type Ia Supernovae in the SDSS Survey
11677 Harvey B. Richer, University of British Columbia Is 47 Tuc Young? Measuring its White Dwarf Cooling Age and Completing a Hubble Legacy
11686 Nahum Arav, Virginia Polytechnic Institute and State University The Cosmological Impact of AGN Outflows: Measuring Absolute Abundances and Kinetic Luminosities
11687 Thomas R. Ayres, University of Colorado at Boulder SNAPing Coronal Iron
11694 David R. Law, University of California - Los Angeles Mapping the Interaction between High-Redshift Galaxies and the Intergalactic Environment
11696 Matthew A. Malkan, University of California - Los Angeles Infrared Survey of Star Formation Across Cosmic Time
11697 Slawomir Stanislaw Piatek, New Jersey Institute of Technology Proper Motion Survey of Classical and SDSS Local Group Dwarf Galaxies
11698 Mary E. Putman, Columbia University in the City of New York The Structure and Dynamics of Virgo's Multi-Phase Intracluster Medium
11700 Michele Trenti, University of Colorado at Boulder Bright Galaxies at z>7.5 with a WFC3 Pure Parallel Survey
11702 Hao-Jing Yan, The Ohio State University Research Foundation Search for Very High-z Galaxies with WFC3 Pure Parallel
11705 Frederick W. Hamann, University of Florida Physical Properties of Quasar Outflows: From BALs to mini-BALs
11707 Kailash Sahu, Space Telescope Science Institute Detecting Isolated Black Holes through Astrometric Microlensing
11719 Julianne Dalcanton, University of Washington A Calibration Database for Stellar Models of Asymptotic Giant Branch Stars
11720 Patrick Dufour, Universite de Montreal Detailed analysis of carbon atmosphere white dwarfs
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
11727 Timothy M. Heckman, The Johns Hopkins University UV spectroscopy of Local Lyman Break Galaxy Analogs: New Clues to Galaxy Formation in the Early Universe
11730 Nitya Jacob Kallivayalil, Massachusetts Institute of Technology Continued Proper Motions of the Magellanic Clouds: Orbits, Internal Kinematics, and Distance
11732 C. S. Kochanek, The Ohio State University Research Foundation The Temperature Profiles of Quasar Accretion Disks
11733 Karen M. Leighly, University of Oklahoma Norman Campus WPVS 007: the little AGN that could
11734 Andrew J. Levan, The University of Warwick The hosts of high redshift gamma-ray bursts
11735 Filippo Mannucci, Osservatorio Astrofisico di Arcetri The LSD project: dynamics, merging and stellar populations of a sample of well-studied LBGs at z~3
11818 Paul Kalas, University of California - Berkeley NICMOS confirmation of an extrasolar planet candidate directly detected with ACS
12019 Christy A. Tremonti, University of Wisconsin - Madison After the Fall: Fading AGN in Post-starburst Galaxies
12119 Amy Simon-Miller, NASA Goddard Space Flight Center Rapid Response: Unexpected Jupiter Impact

Selected highlights

GO 11556: Investigations of the Pluto System

Hubble Space Telescope image of Pluto, Charon and the two new moons, Nix & Hydra Pluto, one of the largest members of the Kuiper Belt and, until recently (still, for some), the outermost planet in the solar system, has been in the news over the last year or two. Besides the extended "planet"/"dwarf planet" debate, Pluto is the primary target of the New Horizons Mission, and Hubble observations in 2005 led to the discovery of two small moons. Together with Charon, itself only discovered in 1978, these additions make Pluto a 4-body system. Christened Nix and Hydra, the two new moons are 5,000 fainter than Pluto itself, implying diameters as small as ~30-50 km if the surface composition is similar to Pluto itself. The present program aims to better characterise these bodies through multicolour observations with WFC3. The observations are phased with a cadence that samples the different orbital periods: 6.4 days for Pluto/Charon; 24.9 days for Nix/Pluto; and 38 days for Hydra/Pluto. The goal is to identify systematic photometric variations that might probe the rotation period, testing whether these moons are in synchronous rotation with Pluto itself.

GO 11707: Detecting Isolated Black Holes through Astrometric Microlensing

A rather spectacular version of black hole lensing. Gravitational lensing is a consequence of general relativity. Its effects were originally quantified by Einstein himself in the mid-1920s. In the 1930s, Fritz Zwicky suggested that galaxies could serve as lenses, but lower mass objects can also also lens background sources. Bohdan Paczynski pointed out in the mid-1980s that this offered a means of detecting dark, compact objects that might contribute to the dark-matter halo. Paczcynski's suggestion prompted the inception of several large-scale lensing surveys, notably MACHO, OGLE, EROS and DUO. Those wide-field imaging surveys have target high density starfields towards the Magellanic Clouds and the Galactic Bulge, and have succeeded in identifying numerous lensing events. The duration of each event depends on several factors, including the tangential motion of the lens and its mass. Long-term events are generally associated with a massive lens. Duration alone is not sufficient to identify a lens as a black hole - a source with very low tangential motion relative to the Sun can produce the same effect. However, microlensing not only leads to flux amplification, but also to small astrometric motions, caused by the appearance and disappearance of features in the lensed light. Those motions serve as a mass discriminant - higher mass lenses produce larger amplitude motions. The expected astrometric signal from a black hole lens is > 1.4 millarcseconds, just measureable with HST. This program aims to capitalise on this fact by searching for lensing by black holes in the Galactic field. The observations target long-duration lensing events in the Galactic Bulge.

GO 11720: Detailed analysis of carbon atmosphere white dwarfs

Basic structure of a white dwarf star White dwarfs are the final evolutionary stage for stars with masses less than approximately seven times that of the Sun. Following extensive mass loss along the red giant branch, the asymptotic giant branch and, finally, as planetary nebulae, the original stars have shrunk to a total masses that are typically around 0.6 to 0.7 that of the Sun and, since they're composed of degenerate material (usually C-O), to sizes comparable with that of the Earth. The outer skin of the white dwarf forms a very thin atmosphere. In most cases, the atmosphere either is hydrogen-rich, and Balmer lines dominate the optical spectrum, or helium dominated. However, in 2007 a handful of white dwarfs were discovered that appear to have atmospheres where the dominant constituent is carbon, with little or no trace of either hydrogen or helium. As yet, the evolutionary path leading to this unusual composition remains unclear. The present program aims to use COS to obtain spectra at near-ultraviolet wavelengths. Those data will serve to probe the surface gravities, and hence the masses, of these stars, set finer limits on the atmospheric composition, and perhaps shed light on the past evolutionary history of these curious objects.

GO 11734: The hosts of high redshift gamma-ray bursts

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 program targets such systems at redshifts z>3, and aims to use WFC3 and ACS observations to reveal the host galaxy.

Past weeks:
page by Neill Reid, updated 19/2/2010