This week on HST


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

Program Number Principal Investigator Program Title
11576 Jean-Michel Desert, Harvard University Physical parameters of the upper atmosphere of the extrasolar planet HD209458b
11585 Neil H. Crighton, Max-Planck-Institut fur Astronomie, Heidelberg Tracing the distribution of gas and galaxies using three closely-spaced background QSOs
11611 D. Michael Crenshaw, Georgia State University Research Foundation Are Narrow-Line Seyfert 1 Galaxies Viewed Pole-on?
11616 Gregory J. Herczeg, Max-Planck-Institut fur extraterrestrische Physik The Disks, Accretion, and Outflows {DAO} of T Tau stars
11641 Mark S. Westmoquette, University College London (UCL) Super star clusters in the starburst core of M82
11696 Matthew A. Malkan, University of California - Los Angeles Infrared Survey of Star Formation Across Cosmic Time
11700 Michele Trenti, University of Colorado at Boulder Bright Galaxies at z>7.5 with a WFC3 Pure Parallel Survey
11737 David M. Meyer, Northwestern University The Distance Dependence of the Interstellar N/O Abundance Ratio: A Gould Belt Influence?
11742 Gabor Worseck, University of California - Santa Cruz Probing HeII Reionization with GALEX-selected Quasar Sightlines and HST/COS
11840 Andrew J. Levan, The University of Warwick Identifying the host galaxies for optically dark gamma-ray bursts
12009 Anja von der Linden, Stanford University Anatomy of a merger: the curious case of MACS J0417.5-1154
12014 Michael R. Garcia, Smithsonian Institution Astrophysical Observatory Continued M31 Monitoring for Black Hole X-ray Nova
12065 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12166 Harald Ebeling, University of Hawaii A Snapshot Survey of The Most Massive Clusters of Galaxies
12169 Boris T. Gaensicke, The University of Warwick The frequency and chemical composition of planetary debris discs around young white dwarfs
12181 Drake Deming, NASA Goddard Space Flight Center The Atmospheric Structure of Giant Hot Exoplanets
12197 Johan Richard, University of Durham Evolution in the Size-Luminosity Relation of HII regions in Gravitationally-lensed galaxies
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
12215 Nancy R. Evans, Smithsonian Institution Astrophysical Observatory Searching for the Missing Low-Mass Companions of Massive Stars
12216 Steve B. Howell, National Optical Astronomy Observatory, AURA Taming the Invisible Monster with COS: Eclipse Spectroscopy of Epsilon Aurigae
12226 R. Michael Rich, University of California - Los Angeles The Hot Stellar Content and HB morphology of the massive globular cluster G1
12272 Christy A. Tremonti, University of Wisconsin - Madison Testing Feedback: Morphologies of Extreme Post-starburst Galaxies
12284 James Muzerolle, Space Telescope Science Institute Light Echoes from a Periodic Protostellar Outburst
12287 Scott D. Friedman, Space Telescope Science Institute Constraining Models of Deuterium Depletion and Galactic Chemical Evolution with Improved Measurements of D/H
12289 J. Christopher Howk, University of Notre Dame A COS Snapshot Survey for z < 1.25 Lyman Limit Systems
12292 Tommaso L. Treu, University of California - Santa Barbara SWELLS: doubling the number of disk-dominated edge-on spiral lens galaxies
12302 Edward F. Guinan, Villanova University Probing the Atmospheres of Cepheids with HST-COS: Pulsation Dependences, Plasma Dynamics and Heating Mechanisms
12320 Brian Chaboyer, Dartmouth College The Ages of Globular Clusters and the Population II Distance Scale
12328 Pieter van Dokkum, Yale University 3D-HST: A Spectroscopic Galaxy Evolution Treasury Part 2

Selected highlights

GO 11585: Tracing the distribution of gas and galaxies using three closely-spaced background QSOs

A computer simulation of gas in the intergalactic medium Galaxy formation, and the overall history of star formation within a galaxy, clearly demands the presence of gas. The detailed evolution therefore depends on how gas is accreted, recycled, circulated through the halo and ejected back into the intergalactic medium. Tracing that evolutionary history is difficult, since gas passes through many different phases, some of which are easier to detect than others. During accretion and subsequent recycling, the gas is expected to be reside predominantly at high temperatures. The most effective means of detecting hot gas is through ultraviolet spectroscopy, where gas associated with relatively nearby galaxies and galaxy clusters systems can be detected as absorption lines superimposed on the spectra of more distant objects, usually quasars. The sampling of galactic halos and the intergalactic medium is usually very sparse, since one cannot place quasars "to order". This program, which is focused on studying the gas in the IGM, takes advantage of the serendipitous presence of three bright quasars (redshifts z~0.7 to 1.2) within~1 arcminute on the sky. The Cosmic Origins Spectrograph will be used to obtain far-UV spectra, covering absorption from both the warm (~10,000 K) and the warm-hot (~100,000 K) intergalactic medium. These observations will be combined with hydrodynamical simulations to characterise the densities, metallicies and kinematics of IGM clouds along these lines of sight.

GO 11616: The Disks, Accretion, and Outflows (DAO) of T Tau stars

Wide-field image, from NOAO, of T Tauri and its immediate environs The T Tauri stage of evolution occurs early in a star's lifetime, within ~10 Myrs of its birth, when it still retains a dense, dust and gas-rich circumstellar disk. During this phase, there is substantial accretion of material onto the central star. This leads to heating of the inner regions of the accretion disk, and significant emission at ultraviolet and X-ray wavelengths. Previous HST programs (e.g. GO 10840 ) have used the STIS and the ACS/SBC to investigate these processes at FUV wavelengths. The present program will extend those investigations using COS, which provides more than an order of magnitude more sensitivity and resolution. The survey will target 32 T Tauri stars, including 26 "classical" T Tauris and 6 "weak-lined" T Tauris (the latter are surrounded by less disk material, and are generally believed to be at a later stage of evolution than the CTTs). COS will be used to measure the emission profiles of an extensive number of lines, probing opacities, temperatures and densities in the disk and outflow regions.

GO 12320: The Ages of Globular Clusters and the Population II Distance Scale

Hubble Heritage image of the globular cluster, M15 Globular clusters are the oldest structures within the Milky Way that are directly accessible to observation. They are relatively simple systems, with relatively simple colour-magnitude diagrams (albeit with some complexities adduced from recent HST observations, see GO 11233 ). Matching those CMDs against theoretical models allows us to set constraints on the age of the oldest stars in the Galaxy, and hence on the age of the Milky Way and the epoch of galaxy formation. However, the accuracy of those age determinations rest crucially on the accuracy of the cluster distance determinations. The clusters themselves lie at distances of several kpc at best, and tens of kpc at worst; thus, direct trigonometric parallax measurements must await microacrsecond astrometric missions. The classical method of deriving distances is main sequence fitting - using nearby stars, with similar chemical abundances and accurate parallax measurements, to map out the main sequence in absolute units, and then scaling the cluster data to fit. The problem with this method is that metal-poor subdwarfs are rare, so even Hipparcos was only able to obtain accurate distances to a handful of stars. The present program aims to improve the distance measurements by using the Fine Guidance Sensors on HST to determine sub-millarcsecond trigonometric parallaxes to 9 subdwarfs, almost doubling the sample available for MS fitting.

GO 12328: 3D-HST: A Spectroscopic Galaxy Evolution Treasury

A grism spectrum of a high-redshift source Throughout its twenty-plus year career, HST has strongly influenced our understanding of numerous research areas within astronomy and astrophysics. Among those, galaxy evolution stands out as a discipline that has been essentially revolutionised by Hubble observations. The original Hubble Deep Field, the product of 10 days observation in December 1995 of a single pointing of Wide Field Planetary Camera 2, demonstrated conclusively that galaxy formation was a far from passive process. The images revealed numerous blue disturbed and irregular systems, characteristic of star formation in galaxy collisions and mergers. Building on this initial progam, the Hubble Deep Field South (HDFS) provided matching data for a second southern field, allowing a first assessment of likely effects due to field to field cosmic variance; the Hubble Ultra-Deep Field (UDF) probed to even fainter magitude with the Advanced Camera for Surveys (ACS); recent deep near-infrared imaging with WFC3 has pushed the redshift limit to beyond z~8; and the Multi-Cycle Treasury CANDELS program is providing a tiered set of observations that complement, in areal coverage and depth, the deep UDF observation. All of these programs rely on deep, high-sensitivity, high resolution imaging. However, WFC3 is also eqipped with grism/prism optical elements, and therefore offers the potential for low-resolution spectroscopy at optical and near-infrared wavelengths. The present program capitalises on that ability, using the near-infrared WFC3/G141 and far-red ACS/G800L grisms to survey subsets of the GOODS-South, AEGIS, UDS and COSMOS fields covered by the CANDELS survey. These data will provide spectroscopic means of probing star formation at redshifts in the range 1 < z < 3.5.

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