This week on HST


HST Programs: August 16, 2010 - August 22, 2010

Program Number Principal Investigator Program Title
11563 Garth D. Illingworth, University of California - Santa Cruz Galaxies at z~7-10 in the Reionization Epoch: Luminosity Functions to <0.2L* from Deep IR Imaging of the HUDF and HUDF05 Fields
11569 Seth Redfield, Wesleyan University Probing the Atomic and Molecular Inventory of a Beta-Pic Analog, the Young, Edge-On Debris Disk of HD32297
11594 John M. O'Meara, Saint Michaels College A WFC3 Grism Survey for Lyman limit absorption at z=2
11596 Aki Roberge, NASA Goddard Space Flight Center Coronagraphic Imaging of Debris Disks Containing Gas
11598 Jason Tumlinson, Space Telescope Science Institute How Galaxies Acquire their Gas: A Map of Multiphase Accretion and Feedback in Gaseous Galaxy Halos
11599 Richard A. Wade, The Pennsylvania State University Distances of Planetary Nebulae from SNAPshots of Resolved Companions
11604 David J. Axon, Rochester Institute of Technology The Nuclear Structure of OH Megamaser Galaxies
11605 Travis Stuart Barman, Lowell Observatory Obtaining the Missing Links in the Test of Very Low Mass Evolutionary Models with HST
11612 Kris Davidson, University of Minnesota - Twin Cities Eta Carinae's Continuing Instability and Recovery - the 2009 Event
11616 Gregory J. Herczeg, Max-Planck-Institut fur extraterrestrische Physik The Disks, Accretion, and Outflows {DAO} of T Tau stars
11634 Carmen Sanchez Contreras, Instituto de Estructura de la Materia Probing the collimation of pristine post-AGB jets with STIS
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
11657 Letizia Stanghellini, National Optical Astronomy Observatory, AURA The population of compact planetary nebulae in the Galactic Disk
11660 Francesca Bacciotti, Osservatorio Astrofisico di Arcetri Investigation Jet Rotation in Young Stars via High Resolution UV Spectra
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
11671 Andrea Ghez, University of California - Los Angeles Kinematic Reconstruction of the Origin and IMF of the Massive Young Clusters at the Galactic Center
11696 Matthew A. Malkan, University of California - Los Angeles Infrared Survey of Star Formation Across Cosmic Time
11714 Howard E. Bond, Space Telescope Science Institute Snapshot Survey for Planetary Nebulae in Local Group Globular Clusters
11718 Julianne Dalcanton, University of Washington The Stellar Halos of Dwarf Galaxies
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
11731 C. S. Kochanek, The Ohio State University Studying Cepheid Systematics in M81: H-band Observations
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
12320 Brian Chaboyer, Dartmouth College The Ages of Globular Clusters and the Population II Distance Scale

Selected highlights

GO 11598: How Galaxies Acquire their Gas: A Map of Multiphase Accretion and Feedback in Gaseous Galaxy Halos

A computer simulation of galactic gas accretion and outflow Galaxy formation, and the overall history of star formation within a galaxy, clearly depends on the presence of gas, and therefore 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 z>1 QSOs that lie at small angular separations from SDSS galaxies at redshifts between z=0.15 and 0.35. The sightlines run through the halos of the galaxies, and the QSOs therefore provide a pencilbeam backlight that probes hot gas in the foreground systems.

GO 11644: A dynamical-compositional survey of the Kuiper belt: a new window into the formation of the outer solar system

The architecture of the outer Solar System The Kuiper Belt lies beyond the orbit of Neptune, extending from ~30 AU to ~50 AU from the Sun, and includes at least 70,000 objects with diameters exceeding 100 km. Setting aside Pluto, the first trans-Neptunian objects were discovered in the early 1990s. Most are relatively modest in size, with diameters of a few hundred km and photometric properties that suggested an icy composition, similar to Pluto and its main satellite, Charon. Over the last three years, a handful of substantially larger bodies have been discovered, with diameters of more than 1000 km; one of the objects, 2003 UB313, is comparable in size to Pluto (2320 km.). At the same time, ground-based surveys, such as the Deep Ecliptic Survey, the Canada-France Ecliptic plane Survey and the Palomar Quest Survey, scanned the ecliptic for fainter, lower-mass objects, with the aim of using their properties to assess the likely chemical composition and dynamical history of the early Solar System. The present program will use Wide Field Camera 3 to push up to 2 magnitudes fainter than these ground-based studies, providing reliable estimates of compositions for a representative sample of KBOs.

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 10718: The Stellar Halos of Dwarf Galaxies

HST ACS image of GR8, one of the dwarf galaxies targeted by this program The metal-poor subdwarf stars that populate the halo of the Milky Way galaxy are generally recognised as fossil remnants of the first major episode of star formation. 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. HST has permitted observations to be extended to other nearby galaxies, notably M31, where a series of programs have probed the structure and composition of its halo at a variety of locations. Most investigations, however, have targeted spiral galaxies. The present program aims to probe much lower mass systems, with observations of three nearby dwarf irregular systems. The central regions of these galaxies were surveyed as part of the ACS Nearby Galaxy Survey Treasury ( the ANGST project ); the present observations will use ACS to survey regions at larger radii, searching for the oldest component of these irregular systems.

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