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This week on HST


HST Programs: September 22 - September 28, 2008


Program Number Principal Investigator Program Title Links
10872 Harry Teplitz, California Institute of Technology Lyman Continuum Emission in Galaxies at z=1.2 Abstract
10884 Gray Wegner, Dartmouth College The Dynamical Structure of Ellipticals in the Coma and Abell 262 Clusters 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
11113 Keith S. Noll, Space Telescope Science Institute Binaries in the Kuiper Belt: Probes of Solar System Formation and Evolution Abstract
11130 Luis Ho, Carnegie Institution of Washington AGNs with Intermediate-mass Black Holes: Testing the Black Hole-Bulge Paradigm, Part II Abstract
11158 R. Michael Rich, University of California - Los Angeles HST Imaging of UV emission in Quiescent Early-type Galaxies Abstract
11167 Sahar S. Allam, Fermi National Accelerator Laboratory A Unique High Resolution Window to Two Strongly Lensed Lyman Break 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
11196 Aaron S. Evans, State University of New York at Stony Brook An Ultraviolet Survey of Luminous Infrared Galaxies in the Local Universe Abstract
11202 Leon Koopmans, Kapteyn Astronomical Institute The Structure of Early-type Galaxies: 0.1-100 Effective Radii Abstract
11210 George Fritz Benedict, University of Texas at Austin The Architecture of Exoplanetary Systems 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
11213 Gerard T. van Belle, California Institute of Technology Distances to Eclipsing M Dwarf Binaries Abstract
11218 Howard E. Bond, Space Telescope Science Institute Snapshot Survey for Planetary Nebulae in Globular Clusters of the Local Group 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
11544 Adam L. Kraus, California Institute of Technology The Dynamical Legacy of Star Formation Abstract
11548 S. Thomas Megeath, University of Toledo NICMOS Imaging of Protostars in the Orion A Cloud: The Role of Environment in Star Formation Abstract

Some selected highlights

GO 10872: Lyman Continuum Emission in Galaxies at z=1.2

Lyman alpha image of the radio galaxy, 4C41.17 In Big Bang cosmology, the early history of the unverise is characterised by three distinct phases: the initial expansion, during which time Big Bang nucleosynthesis occurs, and the universe cools from its initial exceedingly high temperatures; recombination, which occurs at a redshift z~1,100 (or an age of ~400,000 years), when the Universe was cool enough to allow neutral hydrogen to become dominant, leading to high opacity and the cosmic microwave background; and reionisation, when energy sources reionised hydrogen, reducing the opacity of the intergalactic medium and restoring transparency. Reionisation is generally believed to have occurred at a redshift between z~6 and z~20, with the ionising sources either (or both) the first generation of stars (Population III starbursts) and/or proto-quasars. The IGM remains ionised thereafter. A key issue in developing an understanding of this process is assessing how readily starburst-generated Lyman-alpha emission escapes from galaxies, and how starbursts contribute to reionisation at intermediate redshifts. This proposal aims to quantify this matter by targeting galaxies at redshifts 1 < z < 2 for observations at ultraviolet wavelengths with the Advanced Camera for Surveys Solar Blind Channel (ACS/SBC).

GO 11202 The Structure of Early-type Galaxies: 0.1-100 Effective Radii

HST16309+8230, a disk galaxy, distorted due to gravitational lensing by a foreground elliptical Despite their apparently simple appearance, the processes responsible for the formation and evolution of elliptical galaxies remain somewhat obscure. It is clear that most star formationin these systems must occur at early epochs, since these systems are highly gas poor at even moderate redshifts. Grabitational lensing provies one of the more important tools for investigating these systems, since it can probe the detailed form of the mass distribution, and test for the presence of sub-structure in the underlying dark matter, as predicted by some theoretical models. The present program is combining high-resolution, multi-colour HST imaging with ground-based low-resolution VLT/Keck spectroscopic observations of over 50 strong lensing systems. The resultant datasets can be used to investigate the structure of elliptical galaxies over a wide range of radii, and test the predictions of relevant theoretical models.

GO 11210: The Architecture of Exoplanetary Systems

Artist's impression of a young planetary system Immanuel Kant is generally credited with first proposing that the planets in the Solar System coalesced from a flat, rotating disk formed by the Solar Nebula. Direct confirmation of that process only came in the early 1990s, when millimetre-wave interferometers were able to detect molecular gas in Keplerian rotation around a handful of nearby young stars. Since then, there have been numerous other observations, including Hubble's images of proplyds (protoplanetary disks) in the Orion Cluster, and Hubble and Spitzer observations of edge-on disks in other young stars. One of the clear selling points of the Solar Nebula disk model is that it appears to offer a natural path to forming planets with coplanar orbits, matching (most of) our observations of the Solar System. On the other hand, as our knowledge of exoplanetary systems has accumulated over the last decade, it has become clear that dynamical interactions may play a very important role in the evolution of these systems. In particular, disk/planet interactions are generally regarded as responsible for the inward migration of gas giants to form hot Jupiters in <3 day period orbits. Planet-planet interactions could lead to significant changes in orbital inclination. Radial velocity planet searches are uncovering more and more multi-planet systems. This program focuses the high precision of HST's astrometric detectors, the Fine Guidance Sensors, on four of those systems. The aim is to complement the existing radial velocity measurements with sub-milliarcsecond precision astrometry, allowing determination of the true orbital paths - specifically, the relative inclination - of the low-mass objects in these systems.

GO 11548: NICMOS Imaging of Protostars in the Orion A Cloud: The Role of Environment in Star Formation

Millimetre-wave radio map of the Orion molecular clouds The Orion association is the largest nearby star-forming complex, providing a key laboratory for unlocking the secrets of star formation. As such, it has been subject to intense scrutiny at all wavelengths from both ground and space. Surveys at near-infrared and mid-infrared wavelenths, notably by Spitzer, have identified an extensive number of embedded sources, young stellar objects (YSOs) that are still accreting from the surrounding molecular gas. This proposal focuses on one section of the Orion B molecular cloud: a filamentary structure near NGC 2068, a prominent reflection nebula. he goal is to investigate the degree of binarity of YSOs in this complex, probing a range of environments. NICMOS will be used to survey a subset of the candidate YSOs in this region. These observations are an excellent complement to Spitzer since, while NICMOS cannot offer either the same areal coverage or sensitivity at mid-infrared wavelengths, the NIC1 camera can provide a resolution close to 0.1 arcsecond, an order of magnitude higher than the Spitzer images.

Past weeks:
page by Neill Reid, updated 4/9/2008