This week on HST

HST Programs: March 19 - March 25, 2007

Program Number Principal Investigator Program Title Links
10563 Simon Dye, University of Wales, College of Cardiff (UWCC) Accurate dark-matter mass profiles in 3 elliptical galaxies as a test of CDM Abstract
10786 Marc Buie, Lowell Observatory Rotational state and composition of Pluto's outer satellites Abstract
10798 Leon Koopmans, Kapteyn Astronomical Institute Dark Halos and Substructure from Arcs & Einstein Rings Abstract
10802 Adam Riess, Space Telescope Science Institute SHOES-Supernovae, HO, for the Equation of State of Dark energy Abstract
10810 Edwin Bergin, University of Michigan The Gas Dissipation Timescale: Constraining Models of Planet Formation Abstract
10814 Joel Bregman, University of Michigan The Masses for ultraluminous X-ray sources Abstract
10815 Tom Brown, Space Telescope Science Institute The Blue Hook Populations of Massive Globular Clusters Abstract
10833 Bradley Peterson, The Ohio State University Research Foundation Host Galaxies of Reverberation Mapped AGNs Abstract
10849 Stanimir Metchev, University of California - Los Angeles Imaging Scattered Light from Debris Disks Discovered by the Spitzer Space Telescope around 21 Sun-like Star Abstract
10860 Michael Brown, California Institute of Technology The largest Kuiper belt objects Abstract
10862 John Clarke, Boston University Comprehensive Auroral Imaging of Jupiter and Saturn during the International Heliophysical Year Abstract
10877 Weidong Li, University of California - Berkeley A Snapshot Survey of the Sites of Recent, Nearby Supernovae Abstract
10886 Adam Bolton, Smithsonian Institution Astrophysical Observatory The Sloan Lens ACS Survey: Towards 100 New Strong Lenses Abstract
10890 Arjun Dey, NOAO Morphologies of the Most Extreme High-Redshift Mid-IR-Luminous Galaxies Abstract
10910 John Biretta, Space Telescope Science Institute HST / Chandra Monitoring of a Dramatic Flare in the M87 Jet Abstract
10912 Howard Bond, Space Telescope Science Institute Trigonometric Calibration of the Distance Scale for Classical Novae Abstract
10918 Wendy Freedman, Carnegie Institution of Washington Reducing Systematic Errors on the Hubble Constant: Metallicity Calibration of the Cepheid PL Relation Abstract
10930 Stefan Jordan, Universitat Tubingen, Institut fur Astronomie & Astrophysik Mass and Radius of a Near-Chandrasekhar-limit magnetic white dwarf Abstract
10989 George Benedict, University of Texas at Austin Astrometric Masses of Extrasolar Planets and Brown Dwarfs Abstract
11080 Daniela Calzetti, University of Massachusetts Exploring the Scaling Laws of Star Formation Abstract
11085 Bill Sparks, Space Telescope Science Institute Europa in Eclipse: Tenuous Atmosphere, Electromagnetic Activity and Surface Luminescence Abstract

Some selected highlights

GO 10786: Rotational state and composition of Pluto's outer satellites

HST image of Pluto, Charon and the two new moons, Nix & Hydra Pluto, one of the largest members of the Kuiper Belt and, until recently (still, for some), the outermost planet in the solar system, has been in the news over the last year or two. Besides the great "planet"/"dwarf planet" debate, Pluto is the primary target of the New Horizons Mission, and Hubble observations in 2005 led to the discovery of two small moons. Together with Charon, itself only discovered in 1978, these additions make Pluto a 4-body system. Christened Nix and Hydra, the two new moons are 5,000 fainter than Pluto itself, implying diameters as small as ~30-50 km if the surface composition is similar to Pluto itself. The present program aims to better characterise these bodies through multicolour observatioins with WFPC2. The observations will also look for systematic photometric variations that might probe the rotation period. with the aim of testing whether these moons are in synchronous rotation with Pluto itself.

GO 10849: Imaging scattered light from debris disks discovered by Spitzer around 21 sun-like stars

Hubble coronagraphic images of debris disks around two nearby stars, a young M dwarf and a solar-type star Young stars have circumstellar disks, forming due to the conservation of angular momentum as young protostars accrete material from the parent molecular cloud. Initially gas rich T Tauri-like systems, the gas within the disk is largely removed over the first few Myrs, leaving a residual dust-dominated debris disk, perhaps (probably?) populated by number of gas giant and proto-terrestrial planets. The dust disks dissipate with time, becoming more difficult to detect as the star ages and eventually evolving to low density components like the solar zodiacal disk. Over the last few years, Spitzer has revolutionised studies of this field, providing sensitive observations in the thermal mid-infrared that are well tuned to finding the older debris disks around nearby stars. The current program has identified 21 nearby solar-type stars with excess mid-infrared radiation, and aims to use the NICMOS coronagraph to image the debris disks in the scattered light at near-infarred wavelengths.

GO 10877: A Snapshot Survey of the Sites of Recent, Nearby Supernovae

A recent supernova in M100 Supernovae mark the (spectacular) evolutionary endpoint for a subset of stellar systems. Standard models predict that they originate from massive stars and (probably) close binaries with a compact (WD, neutron star) component, but there are still some questions remaining over whether we fully understand the range of possible progenitors. The last decade has seen the development of a number of large-scale programs, usually using moderate-sized telescopes, that are dedicated to monitoring (relatively nearby galaxies, searching for new supernovae. This program obtains follow-up images of recent supernovae, concentrating on systems within 20 Mpc of the Milky Way. The observations are taken well after maximum, with the aim of using the high spatial resolution of WFPC2 to identify the fading remnant and perhaps determine its origin.

Past weeks:
page by Neill Reid, updated 24/3/2007