This week on HST


HST Programs: May 8 - May 14, 2006

Program Number Principal Investigator Program Title Links
10145 Alfred Vidal-Madjar, CNRS, Institut d'Astrophysique de Paris Physical parameters of the upper atmosphere of the extrasolar planet HD209458b Abstract
10482 Howard Bond, Space Telescope Science Institute Trigonometric Calibration of the Period- Luminosity Relations for Fundamental and First-Overtone Galactic Cepheids Abstract
10487 David Ardila, California Institute of Technology A Search for Debris Disks in the Coeval Beta Pictoris Moving Group Abstract
10491 Harald Ebeling, University of Hawaii A Snapshot Survey of the most massive clusters of galaxies Abstract
10494 Leon Koopmans, Kapteyn Institute Imaging the mass structure of distant lens galaxies Abstract
10496 Saul Perlmutter, Lawrence Berkeley National Laboratory Decelerating and Dustfree: Efficient Dark Energy Studies with Supernovae and Clusters Abstract
10503 Gary Da Costa, Australian National University The Star Formation Histories of Early Type Dwarf Galaxies in Low Density Environments: Clues from the Sculptor Group Abstract
10508 William Grundy, Lowell Observatory Orbits, Masses, and Densities of Three Transneptunian Binaries Abstract
10512 William Merline, Southwest Research Institute Search for Binaries Among Faint Jupiter Trojan Asteroids Abstract
10518 Paul Schechter, Massachusetts Institute of Technology Dark matter and the missing images of cx2201-3201 Abstract
10523 Roelof de Jong, Space Telescope Science Institute The Halo Shape and Metallicity of Massive Spiral Galaxies Abstract
10540 Alycia Weinberger, Carnegie Institution of Washington Imaging Nearby Dusty Disks Abstract
10548 Rosa Gonzalez Delgado, Instituto de Astrofisica de Andalucia (IAA) Near-UV Snapshot Survey of Low Luminosity AGNs Abstract
10551 Shri Kulkarni, California Institute of Technology Gamma-Ray Bursts from Start to Finish: A Legacy Approach Abstract
10554 Ray Sharples, University of Durham Globular Cluster Systems of Elliptical Galaxies in Low Density Environments Abstract
10556 David Turnshek, University of Pittsburgh Neutral Gas at Redshift z=0.5 Abstract
10561 Andrea Dieball, University of Southampton A deep UV imaging survey of the Globular Cluster M 30 Abstract
10563 Simon Dye, University of Wales, College of Cardiff Accurate dark-matter mass profiles in 3 elliptical galaxies as a test of CDM Abstract
10564 Jay Farihi, Gemini Observatory, Northern Operations Resolving Ultracool White Dwarf Binaries Abstract
10575 Goran Ostlin, Stockholm University Lyman alpha morphology of local starburst galaxies Abstract
10592 Aaron Evans, State University of New York at Stony Brook An ACS Survey of a Complete Sample of Luminous Infrared Galaxies in the Local Universe Abstract
10624 Derek B. Fox, California Institute of Technology Solving the Mystery of the Short-Hard Gamma-Ray Bursts Abstract
10626 Yeong-Shang Loh, University of Colorado at Boulder A Snapshot Survey of Brightest Cluster Galaxies and Strong Lensing to z = 0.9 Abstract
10627 Margaret Meixner, Space Telescope Science Institute A Snapshot Survey of Post-AGB Objects and Proto-Planetary Nebulae Abstract
10630 Anna Pasquali, Eidgenossiche Technische Hochschule (ETH) The Fine Structure of Elliptical Galaxies in Voids Abstract
10710 Keith Noll, Space Telescope Science Institute Hubble Heritage Observations of ESO 325-G004 Abstract
10775 Ata Sarajedini, University of Florida An ACS Survey of Galactic Globular Clusters Abstract

Some selected highlights

GO 10145: Physical parameters of the upper atmosphere of the extrasolar planet HD209458b

An artist's impression of "Osiris" (HD 209458b) HD 209458 is G0, near-solar metallicity main-sequence dwarf lying 50 parsecs from the Sun. Like (at least) 10% of solar-type stars, it harbours a planetary system, and like (at least) 3% of solar-type stars, it has a `hot Jupiter', orbiting the parent star at a distance of 0.045 AU in a period of 3.52474859 days; HD 209758b's main claim to fame is that it was the first transiting planetary system detected. Transiting planetary systems have proven a goldmine of information on the intrinsic properties of extrasolar giant planets. The orbital inclination is known, and the mass (0.69 MJ), radius (1.32 RJ) and mean density are determined directly. Moreover, HST and Spitzer can be used to probe the planetary atmosphere, by either searching for enhanced absorption during the primary eclipse (HD 209458b transits HD 209458), or by searching for reduced (mid-infrared) emission as HD 209458 eclipses the hot Jupiter. The present proposal aims to build on previous HST observations that detected enhanced Lyman alpha, OI and CII absorption, generally ascribed to gaseous mass-loss (evaporation) from the heated planetary atmosphere. This proposal will use the UV prism on ACS to obtain spectra of HD 209458 with the HRC and SBC detectors. The observations will be made during primary eclipse (transit), with the aim of detecting additional species, such as Fe II and Mg II.

GO 10487: A Search for Debris Disks in the Coeval Beta Pictoris Moving Group

WFPC2 image of Beta Pic's disk Over the last few years, there has been growing recognition of the presence of a number of young stellar associations, each consisting of 20-50 stars, within the Solar Neighbourhood. Beta Pictoris (or Gl 219), a relatively young (~20 Myrs old) A5 dwarf, lying at a distance of just under 20 parsecs form the Sun, is the `flagship' member of one of those groups.. The IRAS satellite originally singled out this A star as unusual, detecting significant excess radiation over the expected photospheric fluxes at mid-infrared wavelengths; Smith & Terrile (1984) used ground-based coronagraphic observations to show that this was due re-radiation from a substantial debris disk. A further 30 stars are associated with this young group, with spectral types ranging from A to late M. Several of these stare are known to also have dusty disks, including the binary HR 7329 (A0 + M7) and the nearby active M1 dwarf, AU Mic (Gl 803). The present proposal aims to extend the sample, using the ACS/HRC in coronagraphic mode to search for debris disks around 21 members of the moving group.

GO 10551: Gamma-Ray Bursts from Start to Finish: A Legacy Approach A

The life history of a gamma-ray burst Gamma ray bursts are described colloquially as the biggest bangs since the Big Bang. Originally detected by US spy satellites in the 1960s, these short-lived bursts of high energy radiation resisted characterisation for over 30 years. It is only within the last decade that the Galactic vs. Extragalactic debate on their origins has been setled in favour of the latter. Generically, gamma ray bursts are believed to originate in the death throes of an extremely massive star, as it collapses to form either a black hole or a highly magnetised neutron star. Most occur at moderate to high redshifts. With the identification of optical counterparts to increasing number of bursts, different patterns of behaviour are emerging, indicating progenitors with a range of intrinsic properties. Gamma ray bursts are, by their nature, unpredictable; thus, follow-up observations are made in Target of Opportunity mode. This proposal triggers with the detection of an appropriate burst by the Swift satellite, and couples multicolour HST ACS imaging with ground-based radio and optical follow-up observations to track its evolution over the following ~300 days.

GO 10554: Globular Cluster Systems of Elliptical Galaxies in Low Density Environments

The giant elliptical, M87, (which is not in a low density environment) has an extensive population of associated globular clusters. Globular clusters are key remnants of the first major episode of star formation in the Milky Way Galaxy. Other galaxies, both spirals and ellipticals, have their own associated populations of globulars; the clusters associated with M31 are well resolved (HST and, to a lesser extent, ground-based observations have resulted in colour-magnitude diagrams), while hundreds of globulars have been identified in M87, the core galaxy in the Virgo cluster. It is likely that those systems, too, are fossils from the earliest stages of galaxy formation. This proposal focuses on low luminosity elliptical galaxies in low density environments. Previous studies suggest that these clusters show a bimodal colour distribution, perhaps indicative of multiple ages and multiple formation epochs. ACS imaging will be used to identify associated globulars, determine the cluster luminosity function and undertake more detailed investigation of the colour distribution.

Past weeks:
page by Neill Reid, updated 4/5/2006