This week on HST


HST Programs: October 17, 2011 - October 23, 2011


Program Number Principal Investigator Program Title
12025 James C. Green, University of Colorado at Boulder COS-GTO: QSO Absorbers, Galaxies and Large-scale Structures in the Local Universe Part 2
12038 James C. Green, University of Colorado at Boulder COS-GTO: COOL, WARM AND HOT GAS IN THE COSMIC WEB AND IN GALAXY HALOS Part 2
12062 Sandra M. Faber, University of California - Santa Cruz Galaxy Assembly and the Evolution of Structure over the First Third of Cosmic Time - III
12101 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12102 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12173 Claus Leitherer, Space Telescope Science Institute Feedback between Stars, ISM and IGM in IR-Luminous Galaxies
12177 Pieter van Dokkum, Yale University 3D-HST: A Spectroscopic Galaxy Evolution Treasury
12188 Jay B. Holberg, University of Arizona Tests of Extreme Physics in Very Cool White Dwarfs
12207 Carles Badenes, Weizmann Institute of Science The past and future evolution of the unique double white dwarf binary SDSS1257+5428
12264 Simon L. Morris, University of Durham The Relationship between Gas and Galaxies for 0
12269 Claudia Scarlata, University of Minnesota - Twin Cities The escape of Lya photons in star-forming galaxies
12276 Bart P. Wakker, University of Wisconsin - Madison Mapping a nearby galaxy filament
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
12286 Hao-Jing Yan, University of Missouri - Columbia Hubble Infrared Pure Parallel Imaging Extragalactic Survey {HIPPIES}
12298 Richard S. Ellis, California Institute of Technology Towards a Physical Understanding of the Diversity of Type Ia Supernovae
12324 C. S. Kochanek, The Ohio State University The Temperature Profiles of Quasar Accretion Disks
12452 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12488 Mattia Negrello, Open University SNAPshot observations of gravitational lens systems discovered via wide-field Herschel imaging
12526 Katherine Anne Alatalo, University of California - Berkeley Mapping Recent Star Formation and Dust in NGC 1266, a Local Example of AGN-driven Feedback
12541 David P. Bennett, University of Notre Dame Measuring the Exoplanet Mass Function Beyond the Snow-Line
12569 Sylvain Veilleux, University of Maryland Ionized and Neutral Outflows in the QUEST QSOs
12586 Kailash C. Sahu, Space Telescope Science Institute Detecting and Measuring the Masses of Isolated Black Holes and Neutron Stars through Astrometric Microlensing
12605 Giampaolo Piotto, Universita di Padova Advances in Understanding Multiple Stellar Generations in Globular Clusters
12665 Mark R. Showalter, SETI Institute Orbital Evolution and Stability of the Inner Uranian Moons

Selected highlights

GO 12060/12062: CANDELS: Galaxy Assembly and the Evolution of Structure over the First Third of Cosmic Time


Part of the GOODS/Chandra Deep Field South field, as imaged by HST
CANDELS is one of three Multi-Cycle Treasury Program, whose observations will be executed over the next three HST Cycles. It builds on past investment of both space- and ground-based observational resources. In particular, it includes coverage of the two fields of the Great Observatory Origins Deep Survey (GOODS), centred on the northern Hubble Deep Field (HDF) in Ursa Major and the Chandra Deep Field-South in Fornax. In addition to deep HST data at optical and near-infrared wavelengths, the fields have been covered at X-ray wavelengths by Chandra (obviously) and XMM-Newton; at mid-infrared wavelengths with Spitzer; and ground-based imaging and spectroscopy using numerous telescopes, including the Kecks, Surbaru and the ESO VLT. This represents an accumulation of almost 1,000 orbits of HST time, and comparable scale allocations on Chandra, Spitzer and ground-based facilities. The CANDELS program is capitalising on this large investment, with new observations with WFC3 and ACS on both GOODS fields, and on three other fields within the COSMOS, EGS and UDS survey areas (see this link for more details). The prime aims of the program are twofold: reconstructing the history of galaxy formation, star formation and nuclear galactic activity at redshifts between z=8 and z=1.5; and searching for high-redshift supernovae to measure their properties at redshifts between z~1 and z~2. The program incorporates a tiered set of observations that complement, in areal coverage and depth, the deep UDF observations, while the timing of individual observations will be set to permit detection of high redshift SNe candidates for subsequent follow-up. The present set of observations is part of the GOODS (South) deep field survey.

GO 12188: Tests of Extreme Physics in Very Cool White Dwarfs


HST ACS images of white dwarfs in the globular cluster, M4
White dwarfs are the evolutionary end point for most stars with masses less than ~7 MSun. These compact degenerate objects lack any internal heat source, and therefore gradually cool from their initial temperatures of ~100,000-200,000K. As they cool, the luminosity decreases from Mbol ~ 2-3 (for the immediate post-PN object) to Mbol ~ 17 (for 10-12 Gyr-old Galactic halo white dwarfs). The rate of cooling is mass dependent (high mass dwarfs cool faster), and can be predicted using sophisticated models of white dwarf interiors. As white dwarfs cool, their spectral characteristics change. The majority of degenerates have hydrogen-rich envelopes with some metallic content (e.g. Ca, Mg), and the spectra are dominated by strong Balmer absorption features at temperatures above ~6,000K (DA white dwarfs). At hot temperatures (>30,000K), a subset of white dwarfs have pure helium atmospheres, and consequently show only helium lines (DB white dwarfs). At cooler temperatures, some metal lines persist, and molecular carbon features are occasionally present, but with ever decreasing temperature, the spectra become featureless and white dwarfs enter the all-embracing DC (featureless spectrum )class. The present program will use near-UV STIS spectroscopy to map the the overall spectral energy distribution at these short wavelengths. The results will be matched against state-of-the-art models, setting constraintsn on the detailed atmosphere composition of these cool objects.

GO 12264: The Relationship between Gas and Galaxies for 0


A computer simulation of galactic gas accretion and outflow
Galaxy formation, and the overall history of star formation within a galaxy, demands the presence of abundant gaseous material. The detailed evolution of individual systems depends on how gas is accreted, recycled, circulated through the halo and, perhaps, 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, probably, subsequent recycling, the gas is expected to be reside predominantly at high temperatures. The most effective means of detecting such gas is through ultraviolet spectroscopy, where gas within nearby systems can be detected as absorption lines superimposed on the spectra of more distant objects, usually quasars. The present program is using the Cosmic Origins Spectrograph to observe four QSOs with redshifts in the range 1 < z < 1.2. All four lie within regions of the sky that have been well surveyed for galaxies, with extensive data already available describing the redshift distribution of large-scale structures along the line of sight. The QSOs provide the background sources, and the goal is to use COS observations with the G130M and G160M gratings to probe hot gas along the line of sight, and match that distribution against the galaxian data.

GO 12488: SNAPshot observations of gravitational lens systems discovered via wide-field Herschel imaging

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 that were being detected and investigates 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. HST has carried out a number of programs following up candidate lenses identified from the Sloan Digital Sky Survey (eg GO 10886 , GO 11289 , GO 12210 ). The present program is using WFCE on HST to obtain follow-up near-infrared (F110W) images of up to 200 candidate lenses selected from the Herschel Astrophysical Terahertz Large Area (H-ATLAS) and the Herschel Multi-tiered Extra-galactic (HerMES) surveys. The HST data will verify the nature of those candidates, and provide the angular resolution necessary to model the mass distribution.

Past weeks:
page by Neill Reid, updated 10/10/2011