This week on HST


HST Programs: March 26 - April 1, 2012


Program Number Principal Investigator Program Title
12192 James T. Lauroesch, University of Louisville Research Foundation, Inc. A SNAPSHOT Survey of Interstellar Absorption Lines
12443 Sandra M. Faber, University of California - Santa Cruz Galaxy Assembly and the Evolution of Structure over the First Third of Cosmic Time - III
12450 C. S. Kochanek, The Ohio State University Understanding A New Class of Mid?IR Transients
12454 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12455 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12460 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12461 Adam Riess, The Johns Hopkins University Supernova Follow-up for MCT
12473 David Kent Sing, University of Exeter An Optical Transmission Spectral Survey of hot-Jupiter Exoplanetary Atmospheres
12474 Boris T. Gaensicke, The University of Warwick The frequency and chemical composition of rocky planetary debris around young white dwarfs
12479 Esther M. Hu, University of Hawaii Low-z Analogs of High Redshift Lyman Alpha Emitters
12486 David V. Bowen, Princeton University QSO Absorption Line Systems from Dwarf Galaxies
12488 Mattia Negrello, Open University SNAPshot observations of gravitational lens systems discovered via wide-field Herschel imaging
12506 Adam L. Kraus, University of Hawaii A Precise Mass-Luminosity-Temperature Relation for Young Stars
12507 Adam L. Kraus, University of Hawaii The Formation and Fundamental Properties of Wide Planetary-Mass Companions
12510 Luc Binette, Universidad Nacional Autonoma de Mexico (UNAM) Quasar Ton 34 with steepest far-UV break known has entered new bal QSO phase
12531 Alex V. Filippenko, University of California - Berkeley Tracking the Continuing Evolution of SN 1993J with COS and WFC3
12540 Robert P. Kirshner, Harvard University UV Studies of a Core Collapse Supernova
12546 R. Brent Tully, University of Hawaii The Geometry and Kinematics of the Local Volume
12548 Jay Farihi, University of Leicester Constraining Planet Formation in the Unique Evolved Binary HR 637 {GJ 86}
12555 Robert Louis da Silva, University of California - Santa Cruz On the Triggering of Quasars During First Passage
12557 Kayhan Gultekin, University of Michigan Low-Mass Black Holes and CIV in Low-Luminosity AGN
12566 Thomas R. Ayres, University of Colorado at Boulder EK Draconis: Warm Coronal Rain?
12572 Michele Trenti, University of Cambridge The Brightest of Reionizing Galaxies Pure Parallel Survey
12603 Timothy M. Heckman, The Johns Hopkins University Understanding the Gas Cycle in Galaxies: Probing the Circumgalactic Medium
12613 Knud Jahnke, Max-Planck-Institut fur Astronomie, Heidelberg Are major galaxy mergers a significant mechanism to trigger massive black hole growth at z=2?
12658 John M. Cannon, Macalester College Fundamental Parameters of the SHIELD Galaxies
12659 Joaquin Vieira, California Institute of Technology Strongly Lensed Dusty Star Forming Galaxies: Probing the Physics of Massive Galaxy Formation
12660 Jonathan D. Nichols, University of Leicester Long term observations of Saturn's northern auroras
12668 Slawomir Stanislaw Piatek, New Jersey Institute of Technology Proper Motion Survey of Classical and SDSS Local Group Dwarf Galaxies
12673 Howard E. Bond, Space Telescope Science Institute HST Observations of Astrophysically Important Visual Binaries
12685 Dean C. Hines, Space Telescope Science Institute Enabling Dark Energy Science for JWST and Beyond
12754 Julia Comerford, University of Texas at Austin Identifying Analogs of NGC 6240: Galaxies with Dual Supermassive Black Holes
12799 Edward M. Sion, Villanova University The Unique Recurrent Nova T Pyxidis: The Transition to Quiescence

Selected highlights

GO 12443: Galaxy Assembly and the Evolution of Structure over the First Third of Cosmic Time - III


Emission line galaxies from the UDS field
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 a subset of the observations will be set to permit detection of high redshift SNe candidates, for subsequent separate follow-up.The present observations focus on wider-field component, obtaining ACS and WFC3 observations in the COSMOS, EGS and UDS fields.

GO 12474: The frequency and chemical composition of rocky planetary debris around young white dwarfs

Artist's impression of a comet spiralling in to the white dwarf variable, G29-38 During the 1980s, one of the techniques used to search for brown dwarfs was to obtain near-infrared photometry of white dwarf stars. Pioneered by Ron Probst (KPNO), the idea rests on the fact that while white dwarfs are hot (5,000 to 15,000K for the typcail targets0, they are also small (Earth-sized), so they have low luminosities; consequently, a low-mass companion should be detected as excess flux at near- and mid-infrared wavelengths. In 1988, Ben Zuckerman and Eric Becklin detected just this kind of excess around G29-38, a relatively hot DA white dwarf that also happens to lie on the WD instability strip. However, follow-up observations showed that the excess peaked at longer wavelengths than would be expected for a white dwarf; rather, G 29-38 is surrounded by a dusty disk. Given the orbital lifetimes, those dust particles must be regularly replenished, presumably from rocky remnants of a solar system. G 29-38 stood as a lone prototype for almost 2 decades, until a handful of other dusty white dwarfs were identified from Spitzer observations within the last couple of years.In subsequent years, a significant number of DA white dwarfs have been found to exhibit narrow metallic absorption lines in their spectra. Those lines are generally attributed to "pollution" of the white dwarf atmospheres. Given that the diffusion time for metals within the atmospheres is short (tens to hundreds of years), the only reasonable means of maintaining such lines in ~20% of the DA population is to envisage continuous accretion from a surrounding debris disk. The present program aims to address this question by using COS to obtain UV observations of young white dwarfs, probing correlations with progenitor mass and examining the detailed composition of the accreted materials.

GO 12506:A Precise Mass-Luminosity-Temperature Relation for Young Stars


Artist's impression of the young, low-mass binary system, Coku Tau4
Mass, luminosity and temperature are the three of the five fundamental quantities that we'd like to know for every star (the other two are chemical composition and age, with age being the least accessible to direct measurement). Binary systems offer one of the most effective means of determining the former three parameters, where measurements of the orbital period and velocity variation permit direct determination of the system mass and, by scaling against angular measurements for visual binaries. the distance. Given the luminosity and temperature, the individual stellar radii can also be derived. These quantities are particularly useful in constraining models of young stars. The present program focuses on observations 16 low-mass systems in nearby star-forming regions. All 16 have orbital determinations, derived from AO-assisted K-band ground-based imaging. the WFC3-UVIS camera will be used to obtain multi-colour imaging, providing measurements of the spectral energy distributions of the individual components in each system, and hence estimates of the surface temperatures.

GO 12668: Proper Motion Survey of Classical and SDSS Local Group Dwarf Galaxies

The low-mass dwarf galaxy, Leo II The Milky Way, m31 and M33 are the three largest galaxies in the Local Group. The system, however, includes more than 25 other members, the majority being dwarf spheroidal galaxies that are satellites of either M31 or the Milky Way. Those galaxies have old, evolved stellar populations, and even the most prominent have masses that are less than a few x 107 MSun, or 10-4 that of the Milky Way. All of these galaxies are moving in the potential set by the overall Local Group system, but dominated by M31 and the Milky Way. Determining full space motions for the dwarfs therefore provide a means of constraining that potential. Even thought the galaxies, and their brightest stellar constituents, are faint, measuring radial velocity is a relatively straightforward procedure. Deriving tangential motions is not, since the typical proper motions of these systems are a few mas/year at best. The present proposal aims to capitalise on the exceptional resolution and high stability of HST to address this issue. WFC3 will target 7 dwarf galaxies, imaging fields that are centred on a background QSO. That QSO serves as a reference point for measurement of the transverse motion of stars in the foreground dwarf galaxy.

Past weeks:
page by Neill Reid, updated 9/3/2012