This week on HST

HST Programs: September 21 - September 27, 2009

Program Number Principal Investigator Program Title Links
11142 Lin Yan, California Institute of Technology Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3 Abstract
11359 Robert W. O'Connell, The University of Virginia Panchromatic WFC3 survey of galaxies at intermediate z: Early Release Science program for Wide Field Camera 3. 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
11559 Imke de Pater, University of California - Berkeley Jovian Upheaval and its Impact on Vortices Abstract
11565 Sebastien Lepine, American Museum of Natural History A search for astrometric companions to very low-mass, Population II stars Abstract
11567 Charles R. Proffitt, Computer Sciences Corporation Boron Abundances in Rapidly Rotating Early-B Stars. Abstract
11600 Benjamin Weiner, University of Arizona Star formation, extinction and metallicity at 0.7 Abstract
11644 Michael E. Brown, California Institute of Technology A dynamical-compositional survey of the Kuiper belt: a new window into the formation of the outer solar system Abstract
11651 Carole A. Haswell, Open University Is the atmosphere of the hottest known transiting exoplanet evaporating? Abstract
11657 Letizia Stanghellini, National Optical Astronomy Observatories The population of compact planetary nebulae in the Galactic Disk Abstract
11704 Brian Chaboyer, Dartmouth College The Ages of Globular Clusters and the Population II Distance Scale Abstract
12007 Garth Illingworth, University of California, Santa Cruz Supernova Follow-up Abstract

Selected highlights

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 (on HST) and mid-infrared (MIPS on Spitzer) wavelengths. The initial observatiosn for this Cycle 16 program were taken with NICMOS, and the program has been transferred to WFC3 for Cycle 17. 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 11565: A search for astrometric companions to very low-mass, Population II stars

HST image of Gliese 623AB, a nearby disk-dwarf binary system Binary stars provide an important avenue for setting constraints on stellar evolution, particularly binary stars that consist of components with significantly different masses. The simplest means of producing stars in a dynamically bound system is during the formation process; consequently, it is reasonable to assume that the the stars are coeval and a comparison between the observed properties and predictions can constrain stellar models. Binary systems are common in stars in the Galactic disk, although the overall frequency does decrease with stellar mass, ranging from ~60-70% for G dwarfs to closer to 20% for late-type M dwarfs and ultracool dwarfs. Binaries are much rarer among the metal-poor members of the Galactic halo, with only a handful known among cool, late-type subdwarfs. The present program aims to expand the sample by using WFC3 on HST to image low-mass, metal-poor subdwarfs within 120 parsecs of the Sun, searching for close, faint companions that can be monitored for astrometric orbit determinations.

GO 11644: A dynamical-compositional survey of the Kuiper belt: a new window into the formation of the outer solar system

The view from Sedna: an artist's impression The Kuiper Belt lies beyond the orbit of Neptune, extending from ~30 AU to ~50 AU from the Sun, and includes at least 70,000 objects with diameters exceeding 100 km. Setting aside Pluto, the first trans-Neptunian objects were discovered in the early 1990s. Most are relatively modest in size, with diameters of a few hundred km and photometric properties that suggested an icy composition, similar to Pluto and its main satellite, Charon. Over the last three years, a handful of substantially larger bodies have been discovered, with diameters of more than 1000 km; one of the objects, 2003 UB313, is comparable in size to Pluto (2320 km.). At the same time, ground-based surveys, such as the Deep Ecliptic Survey, the Canada-France Ecliptic plane Survey and the Palomar Quest Survey, scanned the ecliptic for fainter, lower-mass objects, with the aim of using their properties to assess the likely chemical composition and dynamical history of the early Solar System. The present program will use Wide Field Camera 3 to push up to 2 magnitudes fainter than these ground-based studies, providing reliable estimates of compositions for a representative sample of KBOs.
Past weeks:
page by Neill Reid, updated 23/9/2009