This week on HST

HST Programs: October 2 - October 8, 2006

ACS resumes observations with the Wide-Field Camera

Program Number Principal Investigator Program Title Links
10496 Saul Perlmutter, Lawrence Berkeley National Laboratory Decelerating and Dustfree: Efficient Dark Energy Studies with Supernovae and Clusters Abstract
10519 Janet Simpson, NASA Ames Research Center Testing the Stellar Coalescence and Accretion Disk Theories of Massive Star Formation with NICMOS Abstract
10551 Shri Kulkarni, California Institute of Technology Gamma-Ray Bursts from Start to Finish: A Legacy Approach Abstract
10632 Massimo Stiavelli, Space Telescope Science Institute Searching for galaxies at z>6.5 in the Hubble Ultra Deep Field Abstract
10633 Nial Tanvir, University of Hertfordshire GRB afterglows and host galaxies at very high redshifts Abstract
10763 Shami Chatterjee, Harvard University The Guitar Nebula: A Bow Shock that Traces ISM Turbulence and Accelerates Relativistic Particles Abstract
10795 Timothy Heckman, The Johns Hopkins University The Largest Galaxies in the Local Universe: New Light on Disk Galaxy Formation? Abstract
10802 Adam Riess, Space Telescope Science Institute SHOES-Supernovae, HO, for the Equation of State of Dark energy Abstract
10813 David Bowen, Princeton University MgII Absorption Line Systems: Galaxy Halos or the Metal-Enriched IGM? Abstract
10824 Oleg Gnedin, The Ohio State University Research Foundation Measuring the Shape and Orientation of the Galactic Dark-Matter Halo using Hypervelocity Stars Abstract
10825 Bradford Holden, University of California - Santa Cruz The Formation Epoch of Early-type Galaxies: Constraints from the Fundamental Plane at z=1.3 Abstract
10829 Paul Martini, The Ohio State University Secular Evolution at the End of the Hubble Sequence Abstract
10848 Mark Lacy, Jet Propulsion Laboratory Relating the host galaxies of type-2 quasars to their infrared properties Abstract
10851 Raghvendra Sahai, Jet Propulsion Laboratory Solving the Riddle of the Red Rectangle: Proper Motion Study of a Bipolar Nebula around a Binary Abstract
10852 Glenn Schneider, University of Arizona Coronagraphic Polarimetry with NICMOS: Dust grain evolution in T Tauri stars Abstract
10876 Jean-Paul Kneib, Observatoire de Marseille SL2S: The Strong Lensing Legacy Survey Abstract
10880 Henrique Schmitt, Naval Research Laboratiry The host galaxies of QSO2s: AGN feeding and evolution at high luminosities Abstract
10886 Adam Bolton, Smithsonian Institution Astrophysical Observatory The Sloan Lens ACS Survey: Towards 100 New Strong Lenses Abstract
10893 Peter Garnavich, University of Notre Dame Sweeping Away the Dust: Reliable Dark Energy with an Infrared Hubble Diagram Abstract
10905 R. Tully, University of Hawaii The Dynamic State of the Dwarf Galaxy Rich Canes Venatici I Region Abstract
10906 Sylvain Veilleux, University of Maryland The Fundamental Plane of Massive Gas-Rich Mergers: II. The QUEST QSOs Abstract
10920 Charles Hoopes, The Johns Hopkins University High-Resolution Imaging of Nearby Lyman Break Galaxy Analogs in the GALEX All-Sky Survey Abstract

Some selected highlights

GO 10802: SHOES-Supernovae, HO, for the Equation of State of Dark energy

HST WFPC2 image of NGC 4639, one of the spirals targeted in this program The cosmic distance scale and dark energy are two key issues in modern astrophysics, and HST has played a vital role in probing both. On the one hand, HST has been involved in cosmic distance measurements since its inception, largely through the H0 Key Project, which used WFPC2 to identify and photometer Cepheids in 31 spiral galaxies at distances from 60 to 400 Mpc. On the other, HST is the prime instrument for investigating cosmic acceleration by searching for and following Type Ia supernovae at moderate and high redshift. These two cosmological parameters are directly related, and recent years have seen renewed interest in improving the accuracy of H0 with the realization that such measurements, when coupled with the improved constraints from the Cosmic Microwave Background, provide important constraints on cosmic acceleration and the nature of Dark Energy. The present HST program combines observations that are designed to tackle both questions. NICMOS will be used to observe known Cepheids in several Key Project spirals that have hosted Type Ia supernovae; the near-infrared data will provide more accurate distance estimates for those galaxies, tying together the Cepheid and SN Ia distance scales. At the same time, the ACS/WFC will be used for parallel observations designed to search for high-redshift supernovae, adding further weight to the measurement of cosmic acceleration.

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

HST image WFPC2 image of the Herbig-Haro object HH-30, showing the obscuring circumstellar disk and the jet 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.

GO 10886: The Sloan Lens ACS Survey: Towards 100 New Strong Lenses

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 Sloan sky survey provides a powerful tool for identifying candidate galaxy-galaxy lenses; this program is using HST-ACS imaging to verify the nature of those candidates, and provide the angular resolution necessary to model the mass distribution.

Past weeks:
page by Neill Reid, updated 23/9/2006