This week on HST

HST Programs: October 8 - October 14, 2007

Program Number Principal Investigator Program Title Links
10787 Jane Charlton, The Pennsylvania State University Modes of Star Formation and Nuclear Activity in an Early Universe Laboratory Abstract
10798 Leon Koopmans, Kapteyn Astronomical Institute Dark Halos and Substructure from Arcs & Einstein Rings Abstract
10852 Glenn Schneider, University of Arizona Coronagraphic Polarimetry with NICMOS: Dust grain evolution in T Tauri stars Abstract
10872 Harry Teplitz, California Institute of Technology Lyman Continuum Emission in Galaxies at z=1.2 Abstract
10909 David Bersier, Liverpool John Moores University Exploring the diversity of cosmic explosions: The supernovae of gamma-ray bursts Abstract
10920 Tim Heckman, The Johns Hopkins University High-Resolution Imaging of Nearby Lyman Break Galaxy Analogs in the GALEX All-Sky Survey Abstract
11080 Daniela Calzetti, University of Massachusetts Exploring the Scaling Laws of Star Formation Abstract
11082 Christopher Conselice, Univ. of Nottingham NICMOS Imaging of GOODS: Probing the Evolution of the Earliest Massive Galaxies, Galaxies Beyond Reionization, and the High Redshift Obscured Universe Abstract
11103 Harald Ebeling, University of Hawaii A Snapshot Survey of The Most Massive Clusters of Galaxie Abstract
11107 Timothy M. Heckman, The Johns Hopkins University Imaging of Local Lyman Break Galaxy Analogs: New Clues to Galaxy Formation in the Early Universe Abstract
11126 Kristin Chiboucas, University of Hawaii Resolving the Smallest Galaxies Abstract
11134 Karen Knierman, University of Arizona WFPC2 Tidal Tail Survey: Probing Star Cluster Formation on the Edge Abstract
11143 Andrew J. Baker, Rutgers the State University of New Jersey NICMOS imaging of submillimeter galaxies with CO and PAH redshifts Abstract
11155 Marshall D. Perrin, University of California - Berkeley Dust Grain Evolution in Herbig Ae Stars: NICMOS Coronagraphic Imaging and Polarimetry Abstract
11157 Joseph H. Rhee, University of California - Los Angeles NICMOS Imaging Survey of Dusty Debris Around Nearby Stars Across the Stellar Mass Spectrum Abstract
11158 R. Michael Rich, University of California - Los Angeles HST Imaging of UV emission in Quiescent Early-type Galaxies Abstract
11175 Sandra M. Faber, University of California - Santa Cruz UV Imaging to Determine the Location of Residual Star Formation in Galaxies Recently Arrived on the Red Sequence Abstract
11178 William M. Grundy, Lowell Observatory Probing Solar System History with Orbits, Masses, and Colors of Transneptunian Binaries Abstract
11202 Leon Koopmans, Kapteyn Astronomical Institute The Structure of Early-type Galaxies: 0.1-100 Effective Radii Abstract
11211 George Fritz Benedict, University of Texas at Austin An Astrometric Calibration of Population II Distance Indicators Abstract
11212 Douglas R. Gies, Georgia State University Research Foundation Filling the Period Gap for Massive Binaries Abstract
11219 Alessandro Capetti, Osservatorio Astronomico di Torino Active Galactic Nuclei in nearby galaxies: a new view of the origin of the radio-loud radio-quiet dichotomy? Abstract
11227 Jifeng Liu, Smithsonian Institution Astrophysical Observatory The orbital period for an ultraluminous X-ray source in NGC1313 Abstract
11228 Peter McCullough, Space Telescope Science Institute Extrasolar Planet XO-2b Abstract
11289 Jean-Paul Kneib, Laboratoire d'Astronomie Spatiale SL2S: The Strong Lensing Legacy Survey Abstract
11295 Howard E. Bond, Space Telescope Science Institute Trigonometric Calibration of the Distance Scale for Classical Novae Abstract
11312 Graham Smith, University of Birmingham The Local Cluster Substructure Survey (LoCuSS): Deep Strong Lensing Observations with WFPC2 Abstract
11352 A ndrew Gould, The Ohio State University Research Foundation Mass and distance of the sub-Saturn microlensing planet OGLE-2007-BLG-349Lb Abstract

Some selected highlights

GO 10852: Coronagraphic Polarimetry with NICMOS: Dust grain evolution in T Tauri stars

NICMOS coronagraphic images of GM Aurigae, showing the circumstellar disk The T Tauri phase 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. It is generally agreed that at least giant planet formation occurs during this phase, terminating when the gas dissipates to leave a dusty debris disk. The properties of the resultant planets are likely to depend strongly on the properties of the dust within the circumstellar disk. This program aims to combine coronagraphy with the polarimetric capabilities of NICMOS, HST's near-infrared camera, to study the size distribution of dust particles within the disks surrounding a representative sample of young stellar objects. The forthcoming set of observations will target GM Aurigae, a ~0.8 solar-mass star with an age between 2 and 10 million years that has a substantial circumstellar disk. Multiwavelength measurements strongly suggest that the disk, which likely has a full diameter of ~600 AU, has a central gap, radius ~4 AU; that gap may well have been cleared by a jovian-mass planet.

GO 11082: NICMOS Imaging of GOODS: Probing the Evolution of the Earliest Massive Galaxies, Galaxies Beyond Reionization, and the High Redshift Observational Universe

ACS images of a section of the GOODS fields The Great Observatories Origins Deep Survey, is a large-scale program that is designed to probe galaxy formation and evolution at redshifts from z~1 to z~6. GOODS covers two ~150 sq. arcminute fields, one centred on the Hubble Deep Field and the second on the Chandra Deep Field South, and combines deep oppical/far-red imaging (F435W, F606W, F775W and F850LP filters) using ACS on HST with deep IRAC (3.6 to 8 micron) and MIPS (25 micron) imaging with Spitzer. Chandra data are also available for the bulkd of the field. The present program is supplementing those data with near-infrared H-band (F160W) imaging with NICMOS, coupled (eventually) with parallel ultraviolet observations using the ACS/SBC.

GO 11178: Probing Solar System History with Orbits, Masses, and Colors of Transneptunian Binaries

Preliminary orbital determination for the KBO WW31, based on C. Veillet's analysis of CFHT observations; the linked image shows the improved orbital derivation, following the addition of HST imaging The Kuiper Belt consists of icy planetoids that orbit the Sun within a broad band stretching from Neptune's orbit (~30 AU) to distance sof ~50 AU from the Sun (see David Jewitt's Kuiper Belt page for details). Over 500 KBOs (or trans-Neptunian objects, TNOs) are currently known out of a population of perhaps 70,000 objects with diameters exceeding 100 km. Approximately 2% of the known KBOs are binary (including Pluto, one of the largest known KBOs, regardless of whether one considers it a planet or not). This is a surprisingly high fraction, given the difficulties involved in forming such systems and the relative ease with which they can be disrupted. It remains unclear whether these systems formed from single KBOs (through collisions or 3-body interactions) as the Kuiper Belt and the Solar System have evolved, or whether they represent the final tail of an initial (much larger) population of primordial binaries. These issues can be addressed, at least in part, through deriving a better understanding of the composition of KBOs - and those properties can be deduced by measuring the orbital parameters for binary systems. The present proposal will use the Planetary camera on WFPC2 to determine the relative orbits for several known KBO binaries. Just as with binary stars, the orbital period and semi-major axis give the total system mass, while the mid-infrared properties (measured by Spitzer) allow an assessment of the surface area/diameters; combining these measurements gives an estimate of the mean density.

GO 11289: SL2S - The Strong Lensing Legacy Survey

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 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. The CFHT Legacy survey provides a powerful tool for identifying candidate galaxy-galaxy lenses. Optical ground-based imaging, even from Hawaii, cannot match the results from a 2.4-metre telescope in orbit. Thus, the present program is using WFPC2 imaging to verify the nature of those candidates. The high resolution images can then be analysed to model the underlying mass distribution.

Past weeks:
page by Neill Reid, updated 10/8/2007