This week on HST


HST Programs: February 2 - February 8, 2009


Program Number Principal Investigator Program Title Links
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
11212 Douglas R. Gies, Georgia State University Research Foundation Filling the Period Gap for Massive Binaries Abstract
11236 Harry Teplitz, California Institute of Technology Did Rare, Large Escape-Fraction Galaxies Reionize the Universe? Abstract
11566 Jonathan D. Nichols, Boston University Imaging Saturn's Equinoctal Auroras Abstract
11579 Alessandra Aloisi, Space Telescope Science Institute The Difference Between Neutral- and Ionized-Gas Metal Abundances in Local Star-Forming Galaxies with COS Abstract
11787 Ed Nelan, Space Telescope Science Institute Dynamical Masses and Radii of Four White Dwarf Stars Abstract
11788 George Fritz Benedict, University of Texas at Austin The Architecture of Exoplanetary Systems Abstract
11942 George Fritz Benedict, University of Texas at Austin Increasing the Accuracy of HST Astrometry with FGS1r Abstract
11944 Douglas R. Gies, Georgia State University Research Foundation Binaries at the Extremes of the H-R Diagram Abstract
11962 Adam Riess, The Johns Hopkins University A New Supernova in the Antennae; Narrowing in on the Hubble Constant and Dark Energy Abstract
11966 Michael W. Regan, Space Telescope Science Institute The Recent Star Formation History of SINGS Galaxies Abstract
11967 Rachel Somerville, Space Telescope Science Institute WFPC2 Imaging of the Lockman Hole Abstract
11970 John Clarke, Boston University HST Observations of Titan's Escaping Atmosphere in Transit and in Emission Abstract
11971 Darin Ragozzine, California Institute of Technology A Rare Mutual Event between Satellites of the Dwarf Planet Haumea Abstract

Selected highlights

GO 11130: AGNs with Intermediate-mass Black Holes: Testing the Black Hole-Bulge Paradigm, Part II

Schematic diagram of an active galactic nucleus Active galaxies are characterised by bright, compact nuclei that are the source of strong emission lines due highly ionised material. These phenomena are generally believed to arise in hot gas in an accretion disk, centred on a massive (>106 solar mass) hole; indeed, detailed kinematics for a handful of objects have confirmed the presence of a compact, massive object in the core. Most active galactic nuclei (AGNs) are found in spiral galaxies that possess at least a moderately prominent bulge. The present proposal aims to determine whether AGNs exist within later-type spirals, with less prominent bulge components. At the same time, the proposers hope to probe the lower mass limit for black hole formation, specifically testing whether significant numbers of intermediate-mass (~105 colar mass) black holes form. To examine this issue, this proposal targets lower luminosity galaxies, using WFPC2 to obtain I-band (F814W) images of AGNs selected from SDSS spectroscopy. Those images will be used to characterise the nuclear morphology and determine bulge/disk ratios.

GO 11566: Imaging Saturn's Equinoctal Auroras

Saturnian aurorae Planetary aurorae are stimulated by the influx of charged particles from the Sun, which travel along magnetic field lines and funnel into the atmosphere near the magnetic poles. Aurorae therefore require that a planet has both a substantial atmosphere and a magnetic field. They are a common phenomenon on Earth, sometimes visible at magnetic latitudes more than 40 degrees from the pole, and have also been seen on Jupiter, Saturn, Uranus and Neptune. In August 2009, Saturn reaches its equinox, with the Sun moving into the northern Saturnian hemisphere, and Earth crosses the ring plane in mid-September. As a result, it is now possible to view both Saturnian poles simultaneously. This proposal aims to use the ACS/SBC to study aurorae in the northern hemisphere, and compare their characteristics against observations of southern aurorae from previous years. In particular, the southern aurorae tend to occur in an oval whose centre is displaced from the south (rotational) pole. Does the northern hemisphere exhibit a similar phenomenon?

GO 11967: WFPC2 Imaging of the Lockman Hole

Spitzer IRAC imaging of the Lockman hole The Lockman hole is a small region of sky within the constellation of Ursa Major, lying between the two pointer stars in the Big Dipper and approximately 10 degrees from the Hubble Deep Field Originally identified by Lockman, Jahoda and McCammon in the mid-1980s, this ~4 square degree field has an extremely low column density of HI gas, and is therefore highly transparent to radiation at high energy radiation. In the succeeding years, the Lockman field has been targeted for deep observations at X-ray wavelengths by ROSAT, Chandra, ASCA and XMM, at ultraviolet wavelengths by FUSE, at infrared wavelengths by ISO, Spitzer and, in the near future, Herschel, at sub-millimtere wavelengths with SCUBA, and at radio wavelengths by the VLA and the Giant Metrewave Radio Telescope. Extensive ground-based observations have been obtained at optical wavelengths, but, hitherto, HST observations have been limited in scope. The present program will use WFPC2 to survey the central regions of the Lockman hole in the F606W and F814W filters, providing high spatial resolution morphological information on faint galaxies.

Past weeks:
page by Neill Reid, updated 26/1/2009