This week on HST

HST Programs: September 6, 2010 - September 12, 2010

Program Number Principal Investigator Program Title
11535 James C. Green, University of Colorado at Boulder COS-GTO: Deep Search for an Oxygen Atmosphere on Callisto
11540 James C. Green, University of Colorado at Boulder COS-GTO: Search for Hydrocarbons and Nitriles in Pluto's Atmosphere
11556 Marc W. Buie, Southwest Research Institute Investigations of the Pluto System
11576 Jean-Michel Desert, Harvard University Physical parameters of the upper atmosphere of the extrasolar planet HD209458b
11598 Jason Tumlinson, Space Telescope Science Institute How Galaxies Acquire their Gas: A Map of Multiphase Accretion and Feedback in Gaseous Galaxy Halos
11639 Paula Szkody, University of Washington Catching Accreting WDs Moving into Their Instability Strip{s}
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
11658 David A. Turnshek, University of Pittsburgh Probing the Outer Regions of M31 with QSO Absorption Lines
11663 Mark Brodwin, Smithsonian Institution Astrophysical Observatory Formation and Evolution of Massive Galaxies in the Richest Environments at 1.5 < z < 2.0
11668 Anna Frebel, Smithsonian Institution Astrophysical Observatory Cosmo-chronometry and Elemental Abundance Distribution of the Ancient Star HE1523-0901
11675 Justyn R. Maund, University of Copenhagen, Niels Bohr Institute Stellar Forensics: A post-explosion view of the progenitors of core-collapse supernovae
11686 Nahum Arav, Virginia Polytechnic Institute and State University The Cosmological Impact of AGN Outflows: Measuring Absolute Abundances and Kinetic Luminosities
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
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
11741 Todd Tripp, University of Massachusetts Probing Warm-Hot Intergalactic Gas at 0.5 < z < 1.3 with a Blind Survey for O VI, Ne VIII, Mg X, and Si XII Absorption Systems
11830 Rita M. Sambruna, NASA Goddard Space Flight Center Jets at Intermediate Redshifts: Shedding Light on Emission Mechanisms and Physics
12019 Christy A. Tremonti, University of Wisconsin - Madison After the Fall: Fading AGN in Post-starburst Galaxies
12021 Philip Kaaret, University of Iowa An Irradiated Disk in an Ultraluminous X-Ray Source
12179 Jean-Claude Bouret, CNRS, Laboratoire d'Astrophysique de Marseille The Stellar Winds of Evolved, Braked O-Type Magnetic Oblique Rotators
12181 Drake Deming, NASA Goddard Space Flight Center The Atmospheric Structure of Giant Hot Exoplanets
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
12234 Wesley Fraser, California Institute of Technology Differentiation in the Kuiper belt: a search for silicates on icy bodies.
12245 Mark R. Showalter, SETI Institute Orbital Evolution and Stability of the Inner Uranian Moons
12265 Masami Ouchi, Carnegie Institution of Washington Determining the Physical Nature of a Unique Giant Lya Emitter at z=6.595
12292 Tommaso L. Treu, University of California - Santa Barbara SWELLS: doubling the number of disk-dominated edge-on spiral lens galaxies
12307 Andrew J. Levan, The University of Warwick A public SNAPSHOT survey of gamma-ray burst host galaxies

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 11658: Probing the Outer Regions of M31 with QSO Absorption Lines

The Andromeda spiral galaxy, M31 The major stellar components of spiral galaxies, like the Mlky way and nearby Andromeda, are well known: the disk, the central bulge and the old, metal-poor stellar halo. However, the Milky Way is also surrounded by a halo of hot, gas that is itself embedded within a much more tenuous corona of even hotter, ionised gas. Within that structure lie high velocity clouds. Originally discovered in the 1930s as absorption features in stellar spectra, these clouds have velocities that differ significantly from the rotational velocity along that line of sight, and they are generally believed to be undergoing infall into the Galaxy. The origin and nature of these systems remains uncertain, with some favouring a Galactic origin, driven by star formation and feedback between disk and halo, and others supporting their origin within the warm-hot intergalactic medium. HVCs are not self luminous, so indirect methods need to be applied to examine their characteristics. The most effective is to identify bright sources that lie behind individual systems and, as with their discovery in the 1930s, search the stellar spectra for signature absorption lines produced by material within the cloud. Many, indeed most, of the key absorption features lie at ultraviolet wavelengths, a spectral region that has been opened up with the installation of the Cosmic Origins Spectrograph on HST. Several HST programs in Cycles 17 and 18 are using that technique to study halo gas in galaxies, both in the Milky Way and in external galaxies. the present program aims to use bright quasars in the vicinity of M31 to probe the extended halo of that nearby spiral.

GO 11696: Infrared Survey of Star Formation Across Cosmic Time

A region of massive star formation Star formation is the key astrophysical process in determining the overall evolution of galactic systems, the generation of heavy elements, and the overall enrichment of interstellar and intergalactic material. Tracing the overall evolution through a wide redshift range is crucial to understanding how gas and stars evolved to form the galaxies that we see around us now. The present program builds on the ability of HST to carry out parallel observations, using more than one instrument. While the Cosmic Origins Spectrograph is focused on obtaining ultraviolet spectra of unparalleled signal-to-noise, this program uses the near-infrared grisms mounted on the Wide-Field Camera 3 infrared channel to obtain low resolution spectra between 1 and 1.6 microns of randomly-selected nearby fields. The goal is to search for emission lines characteristic of star-forming regions. In particular, these observations are capable of detecting Lyman-alpha emission generated by star formation at redshfits z > 5.6. A total of up to 40 "deep" (4-5 orbit) and 20 "shallow" (2-3 orbit) fields will be targeted in the course of this observing campaign.

GO 12181: The Atmospheric Structure of Giant Hot Exoplanets

Probing the atmosphere of a transiting exoplanet The first exoplanet, 51 Peg b, was discovered through radial velocity measurements in 1995. 51 Pegb was followed by a trickle, and then a flood of other discoveries, as astronomers realised that there were other solar systems radically different from our own, where "hot jupiters" led to short-period, high-amplitude velocity variations. Then, in 1999, came the inevitable discovery that one of those hot jupiters. HD 209458b, was in an orbit aligned with our line of sight to the star, resulting in transits. Since that date, the number of known transiting exoplanet systems has grown to more than 100, most detected through wide-field photometric surveys with the Kepler satellite providing the highest sensitivity dataset. These transiting systems are invaluable, since they not only provide unambiguous measurements of mass and diameter, but they also provide an opportunity to probe the atmospheric structure by differencing spectra taken during and between primary secondary transit. Such observations are best done from space: indeed, the only successful atmospheric observations to date have been with HST and Spitzer. The present program aims to set these measurements on a systematic basis by targeting 13 transiting exoplanets. The WFC3-IR G141 grism will be used to search for characteristic near-infrared spectral features in those systems.

Past weeks:
page by Neill Reid, updated 12/8/2010