This week on HST

HST Programs: August 11 - August 17, 2008

Program Number Principal Investigator Program Title Links
11101 Gabriela Canalizo, University of California - Riverside The Relevance of Mergers for Fueling AGNs: Answers from QSO Host Galaxies 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
11117 David Kent Sing CNRS, Institut d'Astrophysique de Paris The Search for Atmospheric Water in the Transiting Planet HD189733b Abstract
11122 Bruce Balick, University of Washington Expanding PNe: Distances and Hydro Models Abstract
11129 Enrico V. Held, Osservatorio Astronomico di Padova The Star Formation History of the Fornax Dwarf Spheroidal Galaxy 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
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
11164 David A. Weintraub, Vanderbilt University Molecular Hydrogen Disks Around T Tauri Stars Abstract
11172 Arlin Crotts, Columbia University in the City of New York Defining Classes of Long Period Variable Stars in M31 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
11177 Caryl Gronwall, The Pennsylvania State University The Nature of z=3 Lyman-Alpha Emitters 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
11197 Peter Garnavich, University of Notre Dame Sweeping Away the Dust: Reliable Dark Energy with an Infrared Hubble Diagram Abstract
11202 Leon Koopmans, Kapteyn Astronomical Institute The Structure of Early-type Galaxies: 0.1-100 Effective Radii Abstract
11203 Kevin Luhman, The Pennsylvania State University A Search for Circumstellar Disks and Planetary-Mass Companions around Brown Dwarfs in Taurus Abstract
11205 James Muzerolle , university of Arizona The Effects of Multiplicity on the Evolution of Young Stellar Objects: A NICMOS Imaging Study Abstract
11206 Kai G. Noeske, University of California - Santa Cruz At the cradle of the Milky Way: Formation of the most massive field disk galaxies at z>1 Abstract
11208 Tommaso L. Treu, University of California - Santa Barbara The co-evolution of spheroids and black holes in the last six billion years Abstract
11220 Jeff Cooke, University of California - Irvine Direct Detection and Mapping of Star Forming Regions in Nearby, Luminous Quasars Abstract
11227 Jifeng Liu, Smithsonian Institution Astrophysical Observatory The orbital period for an ultraluminous X-ray source in NGC1313 Abstract
11230 Christopher P. O'Dea, Rochester Institute of Technology HST FUV Observations of Brightest Cluster Galaxies: The Role of Star Formation in Cooling Flows and BCG Evolution 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
11336 Alexander Brown, University of Colorado at Boulder X-ray and UV photoionisation and photoexcitation of pre-main-sequence star transitional disks Abstract
11341 Jason A. Surace, California Institute of Technology Lower Luminosity AGNs at Cosmologically Interesting Redshifts: SEDs and Accretion Rates of z~0.36 Seyferts Abstract
11544 Adam L. Kraus, California Institute of Technology The Dynamical Legacy of Star Formation Abstract
11545 Ben Davies, Rochester Institute of Technology A NICMOS survey of newly-discovered young massive clusters 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 11107: Imaging of Local Lyman Break Galaxy Analogs: New Clues to Galaxy Formation in the Early Universe

Mosaic of HST images of M82, the best-known starburst galaxy Current Big Bang cosmological models predict that the universe should have undergone a global re-ionisation at redshifts between 6 and 20. The first generation of stars is generally tapped as the most likely source of the ionising radiation, perhaps enhanced through merger-stimulated starbursts. Direct observations of those galaxies are not possible at present, although the James Webb Space Telescope is expected to open up observations of these systems. In consequence, there is considerable interest in identifying galaxies at lower redshifts that could serve as analogues for the z>6 systems. Over the last few years, the Galaxy Evolution Explorer (GALEX) has proved an important new tool in identifying candidate objects. GALEX has conducted an all-sky survey at ultraviolet wavelengths, and has uncovered sigificant numbers of UV luminous galaxies at low and moderate redshifts. Many of these galaxies are starbursts, undergoing substantial outbursts of star formation. These galaxies have been categorised as "compact UV luminous galaxies" (UVLGs). These appear to be galaxies that are undergoing small-scale mergers, leading to extensive dissipation and vigorous star formation. The present program is using the ACS/SBC prism and WFPC2 to obtain ultraviolet spectra and R-band images of 31 systems, probing the star formation history and its variation with environment.

GO 11117: The Search for Atmospheric Water in the Transiting Planet HD189733b

Artist's impression of a "hot jupiter" in transit HD 198733 is a 7th magnitude G5 dwarf that lies at a distance of ~20 parsecs from the Sun, in the direction of the constellation of Vulpecula. Like many other nearby solar-type stars, HD 189733 has an associated planetary system, including a hot Jupiter, a ~1.15 MJ gas giant with an orbital period of 2.12 days. Most significantly, that inner planet transits the central star, making HD 189733 the closest transiting system found so far. Transiting systems offer a potential gold-mine for extrasolar planetary studies, since not only is the orbital inclination well defined, but the diameter (and hence the average density) is directly measureable form the eclipse depth, while the atmospheric composition can be probed through line absorption or re-radiated thermal flux. The results from these measurments can be used to test, and improve, theoretical models of extrasolar planets. These observations are best done from space (indeed, the only successful atmospheric observations to date have been with HST and Spitzer). Previous observations with HST have been used to determine accurate radii for HD 189733b (e.g. GO 10923 ); the present program aims to search for evidence of water absorption by differencing NICMOS narrowband images taken before, during and after primary transit.
HST will be taking observations for this program during its 100,000th orbit.

GO 11227: The orbital period for an ultraluminous X-ray source in NGC1313

Artist's impression of an ultraluminous x-ray source Ultraluminous X-ray sources have luminosities that exceed the Eddington luminosity for stellar-mass black holes by one or two orders of magnitude. These systems are found in the outer regions of nearby galaxies, mainly actively star-forming systems. None are known within the Milky Way galaxy. There are currently several models for their origin, including beamed emission from conventional black holes and accretion onto intermediate-mass black holes (IMBH). The latter objects are hypothesised to have masses between 100 and a few thousand MSun, sufficiently low that they can avoid spiraling in to the galactic centres. In both cases, the black hole is hypothesised to lie in a binary system. with the stellar companion providing the accreted material. The present proposal aims to differentiate between those models through photometric of monitoring several sources, notably the extremely active source X-2 in the starburst galaxy, NGC 1313. The aim is to search for periodicities that might establish the orbital period, combine those data with radial velocity measurements, and hence obtain a dynamical estimate for the black hole mass.

GO 11548: The Effects of Multiplicity on the Evolution of Young Stellar Objects: A NICMOS Imaging Study

An image of the orion Nebula superimposed on the 13CO map of Orion A (from this link ). 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 252 sources within the Orion A molecular cloud, the complex that includes the Orion Nebula Cluster. NICMOS is being used to survey a subset of the protostars, where possible including multiple sources within the field of view. The observations are an excellent complement to Spitzer since, while HST cannot offer either the same areal coverage or sensitivity at mid-infrared wavelegths, NICMOS provides a resolution close to 0.1 arcsecond, an order of magnitude higher than the Spitzer images.

Past weeks:
page by Neill Reid, updated 18/5/2008