This week on HST


HST Programs: June 9 - June 15, 2008


Program Number Principal Investigator Program Title Links
10583 Chris Stubbs, Harvard University Resolving the LMC Microlensing Puzzle: Where Are the Lensing Objects ? Abstract
11079 Luciana Bianchi, The Johns Hopkins University Treasury Imaging of Star Forming Regions in the Local Group: Complementing the GALEX and NOAO Surveys 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
11110 Stephan McCandliss, The Johns Hopkins University Searching for Lyman alpha Emission from FUSE Lyman Continuum Candidates Abstract
11113 Keith S. Noll, Space Telescope Science Institute Binaries in the Kuiper Belt: Probes of Solar System Formation and Evolution Abstract
11129 Enrico V. Held, Osservatorio Astronomico di Padova The Star Formation History of the Fornax Dwarf Spheroidal Galaxy Abstract
11130 Luis Ho, Carnegie Institution of Washington AGNs with Intermediate-mass Black Holes: Testing the Black Hole-Bulge Paradigm, Part II Abstract
11142 Lin Yan, California Institute of Technology Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3 Abstract
11155 Marshall D. Perrin, University of California - Berkeley Dust Grain Evolution in Herbig Ae Stars: NICMOS Coronagraphic Imaging and Polarimetry Abstract
11172 Arlin Crotts, Columbia University in the City of New York Defining Classes of Long Period Variable Stars in M31 Abstract
11173 Arlin Crotts, Columbia University in the City of New York Completing an Accurate Map of M31 Microlensing 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
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
11219 Alessandro Capetti, Osservatorio Astronomico di Torino Active Galactic Nuclei in nearby galaxies: a new view of the origin of the radio-loud radio-quiet dichotomy? Abstract
11222 Michael Eracleous, The Pennsylvania State University 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
11235 Jason A. Surace, California Institute of Technology HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies in the Local Universe Abstract
11311 Kailash Sahu, Space Telescope Science Institute The high-amplification microlensing event OGLE-2007-BLG-224: a substellar lens in the Galactic disk or a low-mass stellar lens in the halo Abstract
11340 Jonathan E. Grindlay, Harvard University X-ray Observations of 11 Millisecond Pulsars in M28 Abstract
11342 Margarita Karovska, Smithsonian Institution Astrophysical Observatory X-ray Jets Activity in the Symbiotic System CH Cyg Abstract
11512 Mark Raboin Swain, Jet Propulsion Laboratory Molecules in Exoplanet Atmospheres Abstract
11553 Howard Bond, Space Telescope Science Institute HST Imaging of the Luminous Transient in NGC 300 Abstract

Some selected highlights

GO 10583: Resolving the LMC Microlensing Puzzle: Where Are the Lensing Objects ?

Gravitational microlensing Gravitational lensing is a consequence of general relativity, and the effects were originally quantified by Einstein himself in the mid-1920s. In the 1930s, Fritz Zwicky suggested that galaxies could serve as lenses, but lower mass objects can also also lens background sources. Bohdan Paczynski pointed out in the mid-1980s that this offered a means of detecting dark, compact objects that might contribute to the dark-matter halo. Paczcynski's suggestion prompted the inception of several large-scale lensing surveys, notably MACHO, OGLE, EROS and DUO. These wide-field imaging surveys target high density starfields towards the Magellanic Clouds and the Galactic Bulge, and have succeeded in identifying numerous lensing events. Statistical analysis, however, strongly suggests that both the distribution of event durations and the overall number of lenses are inconsistent with a dark matter component. So what are objects doing the lensing? This program aims to answer that question by using WFPC2 to obtain follow-up images of LMC lensed stars that were detected in the initial MACHO survey. Over a decade has elapsed since the lensing event, sufficient time, in at least some cases, for differential motion to separate lens and background star. Thus HST observations can set limits on the fraction of these events that might be produced by ordinary stars in the Galactic disk or halo.

GO 11142: Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3

NICMOS image of the nearby luminous IR galaxy, Arp 299 Luminous infrared galaxies (LIRGs) have total luminosities that exceed 1011.4 LSun, with most of the energy emitted at wavelengths longward of 10 microns. Many (perhaps most) of these galaxies are interacting or merging disk galaxies, with the excess infrared luminosity generated by warm dust associated with the extensive star formation regions. Many systems also exhibit an active nucleus, and may be in the process of evolving towards an S0 or elliptical merger remnant. The present program is targeting systems with redshifts in the range 0.3 < z < 2.7, combining imaging at near-infrared (NICMOS on HST) and mid-infrared (MIPS on Spitzer) wavelengths. All of the systems already have Spitzer mid-infrared spectra, allowing not only an accurate characterisation of the over all flux distribution, and a \ determination of the total luminosity, but also providing insight into the galaxian dust content and chemical evolution.

GO 11213: Distances to Eclipsing M Dwarf Binaries

Artist's impression of a cool binary system Eclipsing binaries are stellar systems where the orbital plane lies in the line of sight, leading to the components undergoing mutual eclipses. These systems are extremely powerful probes of stellar properties, since (given the appropriate radial velocity measurements) they permit direct measurement of both stellar masses and radii. Accurate distances can also be derived from these systems. These results are particularly interesting for stars near the bottom of the main sequence, approaching the hydrogen buyrning limit. The present program aims to use the Fine Guidance Sensors on HST to determine sub-milliarcsecond trigonometric parallaxes for five M-dwarf binaries: YY Gem, GU Boo, CM Dra, NSVS0103 and TRES-HER0-R

GO 11235: HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies in the Local Universe

NICMOS image of the interacting LIRG, NGC 6090 Luminous infrared galaxies (LIRGs) have total luminosities that exceed 1011.4 LSun, with most of the energy emitted at wavelengths longward of 10 microns. Many (perhaps most) of these galaxies are interacting or merging disk galaxies, with the excess infrared luminosity generated by warm dust associated with the extensive star formation regions. Many systems also have an active nucleus, and may be in the process of evolving towards an S0 or elliptical merger remnant. The present program surveys a total of 88 such systems from the IRAS Revised Bright Galaxy Sample, imaging each system with the H-band F160W filter on the NICMOS NIC2 camera. The observations will be used to probe
  • the luminosity and distribution of star formation activity, particularly embedded star clusters;
  • the presence of AGNs and the relationship between star formation and AGN activity;
  • the correlations between near-infrared emission and the mid-IR structures identified from Spitzer IRAC imaging;
  • the presence of coherent structure, bars or bridges, that might funnel gas into the nuclei;
  • and the overall structural properties of the LIRGS as a function of luminosity and environment
Observations of several interacting systems are scheduled for this week.

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