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HST this week: 252


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This week on HST

HST Programs: September 8 - September 14, 2008

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Program Number Principal Investigator Program Title Links
10884 Gray Wegner, Dartmouth College The Dynamical Structure of Ellipticals in the Coma and Abell 262 Clusters Abstract
11103 Harald Ebeling, University of Hawaii A Snapshot Survey of The Most Massive Clusters of Galaxies 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
11144 Richard Bouwens, University of California, Santa Cruz Building on the Significant NICMOS Investment in GOODS: A Bright, Wide-Area Search for z>=7 Galaxies Abstract
11151 Gregory J. Herczeg, California Institute of Technology Evaluating the Role of Photoevaporation of Protoplanetary Disk Dispersal Abstract
11156 Kathy Rages, SETI Institute Monitoring Active Atmospheres on Uranus and Neptune 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
11196 Aaron S. Evans, State University of New York at Stony Brook An Ultraviolet Survey of Luminous Infrared Galaxies in the Local Universe Abstract
11212 Douglas R. Gies, Georgia State University Research Foundation Filling the Period Gap for Massive Binaries Abstract
11218 Howard E. Bond, Space Telescope Science Institute Snapshot Survey for Planetary Nebulae in Globular Clusters of the Local Group Abstract
11235 Jason A. Surace, California Institute of Technology HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies in the Local Universe Abstract
11291 Kris Davidson, University of Minnesota - Twin Cities Following Eta Carinae's Change of State 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 11113: Binaries in the Kuiper Belt: Probes of Solar System Formation and Evolution

A composite of HST images of the Kuiper Belt binary, WW31 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 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. This proposal will use WFPC2 imaging of known KBOs to identify new binary systems.

GO 11144: Building on the Significant NICMOS Investment in GOODS: A Bright, Wide-Area Search for z>=7 Galaxies

Part of the GOODS/Chandra Deep Field South field, as imaged by HST The Great Observatory Origins Deep Survey (GOODS) is a multi-wavelength survey that covers two 150 sq. arcmin. fields, 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. The prime aim of the GOODS program is to reconstruct the history of galaxy formation, star formation and nuclear galactic activity from the epoch of reionisation to the present. The present HST program builds on past results and aims to push observations to the highest redshifts, searching for galaxies at z > 7. Previously obtained GOODS data have been used to identify z-H dropouts - objects visible on F160W NICMOS images, but not on F098 ACS images. Deeper NICMOS images of those candidates will be obtained in the J-band (F110W filter) to confirm whether the fluxes are consistent with 7 < z < 8 star-forming galaxies.

GO 11175: UV Imaging to Determine the Location of Residual Star Formation in Galaxies Recently Arrived on the Red Sequence

Galaxy mergers and the red sequence

The overwhelming majority of galaxies are found in clusters. Observations show that almost all well-defined cluster systems at low and moderate redshift have a significant population of elliptical galaxies which have red colours, indicative of old stellar populations and minimal current star formation. The elliptical galaxies outline a distinct sequence in the colour-magnitude (or colour-mass) diagram, the so-called red sequence. Over the last few years, there has been considerable interest in understanding the origins of this sequence: how did the ellipticals form (most theories envisage mergers of gas-rich systems at moderate redshifts)? when did star formation cease in these galaxies (most galaxies in clusters at redshifts 1.5 < z < 3 seem to have active star formation)? are there environmentally-dependent effects? This proposal aims to address some of these questions through WFPC2 BVI and ACS/SBC observations of a number of low-redshift (0.04 < z < 0.10) galaxies that appear to have only recently arrived on the red sequence. The WFPC2 data will provide detailed morphologies, while the SBC ultraviolet imaging will be ued to search for traces of residual star formation.

GO 11544: The Dynamical Legacy of Star Formation

The central regions of the young star cluster, IC 348 General indications are that the overwhleming majority of stars in the Galactic disk form within clusters. Understanding the cluster environment is therefore important to understanding how most stars - and any associated planetary systems - form and evolve. Star-star interactions can lead to truncation of nascent disks, disruption of binary systems and even ejection from the cluster. The present program aims to investigate these issues by surveying the young star cluster, IC 348, with WFPC2, and combining the present set of observations with data from past cycles. Accurate relative astrometry will enable measurement of the relative stellar motions, and hence the cluster velocity dispersion, as well as premitting the identification of any stars with unusually high motions. In addition, these new WFPC2 images will push observations to fainter limits, potentially revealing new substellar-mass cluster members.
Past weeks:
page by Neill Reid, updated 4/9/2008