This week on HST

HST Programs: July 27 - August 2, 2009

SMOV still under way, but science observations being made.

Program Number Principal Investigator Program Title Links
11196 Aaron S. Evans, State University of New York at Stony Brook An Ultraviolet Survey of Luminous Infrared Galaxies in the Local Universe Abstract
11564 David Kaplan, University of California - Santa Barbara Optical and Ultraviolet Photometry of Isolated Neutron Stars Abstract
11565 Sebastien Lepine, American Museum of Natural History A search for astrometric companions to very low-mass, Population II stars Abstract
11603 Jennifer Andrews, Louisiana State University and A & M College A Comprehensive Study of Dust Formation in Type II Supernovae with HST, Spitzer and Gemini Abstract
11628 Eva Noyola, Max-Planck-Institut fur extraterrestrische Physik Globular Cluster Candidates for Hosting a Central Black Hole Abstract
11657 Letizia Stanghellini, National Optical Astronomy Observatories The population of compact planetary nebulae in the Galactic Disk Abstract
11683 Ming Sun, The University of Virginia Intracluster star formation and galaxy transformation: ESO 137-001 in A3627 Abstract
11706 Peter McCullough, Space Telescope Science Institute The Parallax of the Planet Host Star XO-3 Abstract
11788 George Fritz Benedict, University of Texas at Austin The Architecture of Exoplanetary Systems Abstract

Selected highlights

GO 11196: An Ultraviolet Survey of Luminous Infrared Galaxies in the Local Universe

A 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 exhibit an active nucleus, and may be in the process of evolving towards an S0 or elliptical merger remnant. These two programs build on a previous ACS survey of 88 systems from the IRAS Revised Bright Galaxy Sample (GO 10592) in the F439W and F814W passbands. Program GO 11196 is using the ACS/SBC and WFPC2 to obtain far- (F140LP) and near- (F218W) UV imaging of 27 galaxies; a separate4 program, GO 11235, used NICMOS to obtain near-infrared H-band images of the galaxy cores. Combined with the previously obtained B- and I-band data, these observations will probe
  • the distribution of star formation activity and the presence of bars and bridges, funneling gas towards active regions
  • the age distribution of star clusters
  • the relationship between star formation and AGN activity
  • 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;
  • the overall structural properties of the LIRGS as a function of luminosity and environment
The observations will also provide a detailed UV images for a reference sample of nearby galaxies. Observations of several interacting system are scheduled for this week.

GO 11628: Globular Cluster Candidates for Hosting a Central Black Hole

Artist's impression of the visual distortions introduced by a black hole in a globular cluster The formation, and subsequent evolution, of intermediate-mass black holes (IMBHs) is a process of considerable importance for understanding th development of active galactic nuclei at high redshifts. IMBHs are generally expected to originate in globular-cluster-mass structures; hence, one might expect such objects to be present in some present-day Galactic clusters, particularly those that have undergone dynamical core collapse. The present program aims to obtain detailed measurements of the central radial profiles of a number of globulars, searching for systems with weak cusps that might indicate the presence of central IMBH. The targets are globulars with high central concentrations, including NGC 5946, NGC 6256, NGC 6342 and NGC 6355

GO 11706: The parallax of the transiting planet XO-3

Artist's impression of a planetary transit against an active solar-type star Transiting extrasolar planets offer the opportunity to gain valuable insight into the interior structure and atmospheres of gas giants beyond the Solar System. Besides providing direct measures of mass (with no complications for v sin(i)) and radius (from accurate time-series photometry), spectroscopic observations obtained during either transit or planetary eclipse can probe the atmospheric structure and chemical composition. The present proposal targets the transiting system designated XO-3, which was discovered in 2007 by an international team of professional and amateur astronomers using a fleet of telescopes with very modest apertures - the primary survey telescope, the XO telescope, is a pair of 200-mm telephoto lenses - but a very wide field of view. These small telescopes are used to survey large areas of the celestial sphere, searching for photometric variations characteristic of planetary transits (i.e. periodic dips in brightness of 1-2%); transit candidates are then verified using higher accuracy photometric observations with larger telescopes, and finally radial velocity measurements to confirm the companion mass. XO-3b, the third system discovered in the course of this program, is a ~11.8 MJ object in a 3.2-day period around a 9th magnitude F5 dwarf. Photometric and spectrosopic parallaxes place the star at a distance of around 250 parsecs, with an uncertainty of 15-20%. The present program will use the HST Fine Guidance Sensors to measure a trigonometric parallax accurate to 0.2 milliarcseconds, corresponding to uncertainties of ~5% in distance.

Past weeks:
page by Neill Reid, updated 24/9/2009