This week on HST

HST Programs: December 28, 2009 - January 3, 2010

Program Number Principal Investigator Program Title Links
11108 Esther M. Hu, University of Hawaii Near Infrared Observations of a Sample of z~6.5-6.7 Galaxies Abstract
11149 Eiichi Egami, University of Arizona Characterizing the Stellar Populations in Lyman-Alpha Emitters and Lyman Break Galaxies at 5.7 Abstract
11189 Nial R. Tanvir, University of Leicester Probing the early universe with GRBs Abstract
11202 Leon Koopmans, Kapteyn Astronomical Institute The Structure of Early-type Galaxies: 0.1-100 Effective Radii Abstract
11235 Jason A. Surace, California Institute of Technology HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies in the Local Universe Abstract
11360 Robert W. O'Connell, The University of Virginia Star Formation in Nearby Galaxies Abstract
11522 James Green, University of Colorado COS-GTO: STAR FORMATION/LYMAN-ALPHA Abstract
11524 James Green, University of Colorado COS-GTO: WARM AND HOT ISM IN AND NEAR THE MILKY WAY Abstract
11541 James Green, University of Colorado COS-GTO: COOL, WARM AND HOT GAS IN THE COSMIC WEB AND IN GALAXY HALOS Abstract
11565 Sebastien Lepine, American Museum of Natural History A search for astrometric companions to very low-mass, Population II stars Abstract
11584 Kristin Chiboucas, University of Hawaii Resolving the Smallest Galaxies with ACS Abstract
11588 Raphael Gavazzi, CNRS, Institut d'Astrophysique de Paris Galaxy-Scale Strong Lenses from the CFHTLS survey Abstract
11594 John M. O'Meara, Saint Michaels College A WFC3 Grism Survey for Lyman limit absorption at z=2 Abstract
11597 S. Adam Stanford, University of California - Davis Spectroscopy of IR-Selected Galaxy Clusters at 1 < z < 1.5 Abstract
11599 Richard A. Wade, The Pennsylvania State University Distances of Planetary Nebulae from SNAPshots of Resolved Companions Abstract
11613 Roelof S. de Jong, Astrophys. Inst. Potsdam GHOSTS: Stellar Outskirts of Massive Spiral Galaxies Abstract
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 Abstract
11657 Letizia Stanghellini, National Optical Astronomy Observatories The population of compact planetary nebulae in the Galactic Disk Abstract
11661 Misty C. Bentz, University of California - Irvine The Black Hole Mass - Bulge Luminosity Relationship for the Nearest Reverberation-Mapped AGNs Abstract
11666 Adam J. Burgasser, Massachusetts Institute of Technology Chilly Pairs: A Search for the Latest-type Brown Dwarf Binaries and the Prototype Y Dwarf Abstract
11696 Matthew A. Malkan, University of California - Los Angeles Infrared Survey of Star Formation Across Cosmic Time Abstract
11697 Slawomir Stanislaw Piatek, New Jersey Institute of Technology Proper Motion Survey of Classical and SDSS Local Group Dwarf Galaxies Abstract
11700 Michele Trenti, University of Colorado at Boulder Bright Galaxies at z>7.5 with a WFC3 Pure Parallel Survey Abstract
11703 Stephen E. Zepf, Michigan State University The Nature of the Black Hole in a NGC 4472 Globular Cluster and the Origin of Its Broad [OIII] Emission Abstract
11706 Peter McCullough, Space Telescope Science Institute The Parallax of the Planet Host Star XO-3 Abstract
11714 Howard E. Bond, Space Telescope Science Institute Snapshot Survey for Planetary Nebulae in Local Group Globular Clusters Abstract
11718 Julianne Dalcanton, University of Washington The Stellar Halos of Dwarf Galaxies Abstract
11719 Julianne Dalcanton, University of Washington A Calibration Database for Stellar Models of Asymptotic Giant Branch Stars Abstract
11732 C. S. Kochanek, The Ohio State University Research Foundation The Temperature Profiles of Quasar Accretion Disks Abstract
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 Abstract
11742 Gabor Worseck, University of California - Santa Cruz Probing HeII Reionization with GALEX-selected Quasar Sightlines and HST/COS Abstract
11788 George Fritz Benedict, University of Texas at Austin The Architecture of Exoplanetary Systems Abstract
11803 Holland Ford, The Johns Hopkins University Observing Cluster Assembly Around the Massive Cluster RXJ0152-13 Abstract

Selected highlights

GO 11565: A search for astrometric companions to very low-mass, Population II stars

HST image of Gliese 623AB, a nearby disk-dwarf binary system Binary stars provide an important avenue for setting constraints on stellar evolution, particularly binary stars that consist of components with significantly different masses. The simplest means of producing stars in a dynamically bound system is during the formation process; consequently, it is reasonable to assume that the the stars are coeval and a comparison between the observed properties and predictions can constrain stellar models. Binary systems are common in stars in the Galactic disk, although the overall frequency does decrease with stellar mass, ranging from ~60-70% for G dwarfs to closer to 20% for late-type M dwarfs and ultracool dwarfs. Binaries are much rarer among the metal-poor members of the Galactic halo, with only a handful known among cool, late-type subdwarfs. The present program aims to expand the sample by using WFC3 on HST to image low-mass, metal-poor subdwarfs within 120 parsecs of the Sun, searching for close, faint companions that can be monitored for astrometric orbit determinations.

GO 11613: GHOSTS: Stellar Outskirts of Massive Spiral Galaxies

The (relatively) nearby barred spiral galaxy, NGC 253 The subdwarf stars that populate the Galactic halo are generally recognised as fossil remnants of the first episode of substantial star formation to afflict the Milky Way galaxy. The structure and density distribution of our own halo has been inferred partly from deep starcounts, partly from globular cluster systems and partly from the kinematics of local subdwarfs; most analyses favour a near-spherical system with density r-3.5. The aim of this proposal is to extend these studies to a number of other nearby spiral systems. ACS and WFC3/UVIS are being used to obtain SNAP observations in the F606W and F814W filters in regions within the galactic halos. The observations are capable of obtaining photometry extending 2-3 magnitudes below the tip of the red giant branch in those galaxies. The data should permit separation of the contributions from disk, thick disk and bulge, and isolation of the halo population. The observations will allow measurement of the halo metallicity distribution and an estimate of the shape of the halo in these systems.

GO 11706: The parallax of the transiting planet XO-3

Artist's impression of a planetary transit against an active solar-type star Transiting extrasolar planets offer the opportunity to gain valuable insight into the interior structure and atmospheres of gas giants beyond the Solar System. Besides providing direct measures of mass (with no complications for v sin(i)) and radius (from accurate time-series photometry), spectroscopic observations obtained during either transit or planetary eclipse can probe the atmospheric structure and chemical composition. The present proposal targets the transiting system designated XO-3, which was discovered in 2007 by an international team of professional and amateur astronomers using a fleet of telescopes with very modest apertures - the primary survey telescope, the XO telescope, is a pair of 200-mm telephoto lenses - but a very wide field of view. These small telescopes are used to survey large areas of the celestial sphere, searching for photometric variations characteristic of planetary transits (i.e. periodic dips in brightness of 1-2%); transit candidates are then verified using higher accuracy photometric observations with larger telescopes, and finally radial velocity measurements to confirm the companion mass. XO-3b, the third system discovered in the course of this program, is a ~11.8 MJ object in a 3.2-day period around a 9th magnitude F5 dwarf. Photometric and spectrosopic parallaxes place the star at a distance of around 250 parsecs, with an uncertainty of 15-20%. The present program will use the HST Fine Guidance Sensors to measure a trigonometric parallax accurate to 0.2 milliarcseconds, corresponding to uncertainties of ~5% in distance.

GO 11741: 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

Probing the intergalactic medium via QSO absorption lines One of the key issues facing modern cosmology is the "missing baryon" problem. In brief, a census of all the constituents in the local universe accounts for less than half of the baryonic mass expected based on measurements of the fractional abundanmce of deuterium and observations of the cosmic microwave background. It is generally believed that the missing material lurks in the form of extremely hot gas in the intergalactic medium. The most effective means of probing that medium, and testing this hypothesis, is to search for the appropriate absorption lines in the spectrum of a background source. QSOs are particularly effective cosmic searchlights, since they have strong continuum flux levels at the ultraviolet wavelengths where most of the important absorption lines fall. Following SM4, and the installation of the Cosmic Origins Spectrograph, HST is now well equipped to tackle this type of program, and search fgor a full accounting of the baryonic universe. The present program weill use COS to obtain spectra of nine QSOs at redshifts beyond z=0.89, and will search for warm-hot intergalactic gas in the redshift range 0.5 < z < 1.3.

Past weeks:
page by Neill Reid, updated 23/10/2009