This week on HST


HST Programs: April 10 - April 16, 2006


Program Number Principal Investigator Program Title Links
10125 Karen Leighly, University of Oklahoma Norman Campus Where is the Wind in 1H0707-495? Abstract
10433 Barry Madore, Carnegie Institution of Washington The Cepheid PL-Z Abstract
10487 David Ardila, California Institute of Technology A Search for Debris Disks in the Coeval Beta Pictoris Moving Group Abstract
10488 Mariangela Bernardi, University of Pennsylvania The Most Massive Galaxies in the Universe: Color-Gradients and Texture Abstract
10496 Saul Perlmutter, Lawrence Berkeley National Laboratory Decelerating and Dustfree: Efficient Dark Energy Studies with Supernovae and Clusters Abstract
10507 Denis Grodent, Universite de Liege High resolution imaging of Jupiter's diffuse auroral emissions inside and outside the main oval during solar minimum. Abstract
10512 William Merline, Southwest Research Institute Search for Binaries Among Faint Jupiter Trojan Asteroids Abstract
10514 Keith Noll, Space Telescope Science Institute Kuiper Belt Binaries: Probes of Early Solar System Evolution Abstract
10518 Paul Schechter, Massachusetts Institute of Technology Dark matter and the missing images of cx2201-3201 Abstract
10519 Janet Simpson, NASA Ames Research Center Testing the Stellar Coalescence and Accretion Disk Theories of Massive Star Formation with NICMOS Abstract
10527 Dean Hines, Space Science Institute Imaging Scattered Light from Debris Disks Discovered by the Spitzer Space Telescope Around 20 Sun-like Stars Abstract
10533 Joana Oliveira, University of Keele The IMF in NGC6611: the environmental influence on the formation of low-mass stars and brown dwarfs Abstract
10539 Karl Stapelfeldt, Jet Propulsion Laboratory Coronagraphic Imaging of Bright New Spitzer Debris Disks Abstract
10545 Michael Brown, California Institute of Technology Icy planetoids of the outer solar system Abstract
10549 Robert Kirshner, Harvard University SAINTS - Supernova 1987A INTensive Survey Abstract
10550 Markus Kissler-Patig, European Southern Observatory - Germany The Nature of LSB galaxies revealed by their Globular Clusters Abstract
10556 David Turnshek, University of Pittsburgh Neutral Gas at Redshift z=0.5 Abstract
10559 Herve Bouy, Instituto de Astrofisica de Canarias Astrometric monitoring of binary L and T dwarfs Abstract
10564 Jay Farihi, Gemini Observatory, Northern Operations Resolving Ultracool White Dwarf Binaries Abstract
10587 Adam Bolton, Smithsonian Institution Astrophysical Observatory Measuring the Mass Dependence of Early-Type Galaxy Structure Abstract
10588 Michael Brotherton, University of Wyoming The Host Galaxies of Post-Starburst Quasars Abstract
10592 Aaron Evans, State University of New York at Stony Brook An ACS Survey of a Complete Sample of Luminous Infrared Galaxies in the Local Universe Abstract
10603 Deborah Padgett, California Institute of Technology Multiwavelength Imaging of Edge-on Protoplanetary Disks: Quantifying the Growth of Circumstellar Dust Abstract
10625 Philippe Lamy, Laboratoire d'Astronomie Spatiale A Multiwavelength Investigation of Comet 73P/SW3-C Abstract
10718 Jeff Valenti, Space Telescope Science Institute The Exosphere of a Newly Discovered Transiting Planet Abstract
10775 Ata Sarajedini, University of Flordia An ACS Survey of Galactic Globular Clusters Abstract
10782 Imke de Pater, University of California - Berkeley Quit winking: Jupiter opens its other eye Abstract

Some selected highlights

GO 10512: A search for Binaries Among Faint Jupiter Trojan Asteroids

An artist's impression of the binary asteroid, Patroclus Binary stars have been known for well over 300 years, but it is only within the last decade that it has been clear that asteroids are also often found in pairs. This is somewhat unexpected, since the low mass of asteroids leads to very low binding energy between the components. Both the formation mechanism(s?) and the stability of current systems remain unclear. The present program is using the HRC on ACS to carry out a snapshot survey of faint Trojan asteroids, which reside at the stable L4 and L5 Lagrange points on Jupiter's orbit. Several larger Trojans are known to be binary (e.g. Patroclus, see this link for more information), but data remain spare for the fainter members of this population. The collision environment among the Trojans is similar to that of Main Belt asteroids, but the composition is likely to be very different; thus, sampling the binary fraction over a significant range in mass should help us understand the relative importance of collisional and binary formation mechanisms.

GO 10518: Dark matter and the missing images of cx2201-3201

Subaru images of the lensed quasar, PG1115+080; the lensing galaxy is the reddish central object Gravitational lensing is a consequence the theory of general relativity. Its importance as an astrophysical tool first became apparent with the realisation (in 1979) that the quasar pair Q0957+561 actually comprised two lensed images of the same background quasar. In the succeeding years, lensing has been used to probe the mass distribution of galaxies (mainly through multiply-imaged quasars), galaxy clusters (arcs and arclets) and the large-scale mass distribution (weak lensing). The present program centres on cx2202-3201, a z=3.9 quasar that is leing lensed by a foreground disk galaxy. Ground-based observations have been used to identify 2 lensed images, but a total of 4 are expected if the lensing mass follows the disk; if there are really only two images, then most of the mass must reside in a dark halo. The proposal will use ACS imaging to search for the missing images.

GO 10533: The IMF in NGC6611: the environmental influence on the formation of low-mass stars and brown dwarfs

WFPC2 HST image of the Eagle nebula, part of NGC6611 The Eagle nebula occupies the central regions of the NGC 6611 (or Messier 16) nebula. Lying at a distance of approximately 2 kpc, NGC 6611 is the site of substantial on-going star formation. The central cluster, which includes a number of O-type stars, is approximately 5 million years old (comparable with the Orion Nebula Cluster), and remains embedded within the dust and gas of the parent cloud. Unlike Orion, M16 has a relatively low star density, although the O stars provide a similar high intensity of ionising radiation. This proposal will use NICMOS and ACS to obtain deep images in the F814W (I), F850LP (z), F110W (J) and F160W (H) filters, and aims to use the resultant colour-magnitude diagrams to probe the initial mass function through low-mass stars to brown dwarfs with masses of 20-30 MJup. The results from this investigation can be compared with similar data for stars forming in a range of other environments.

GO 10549: SAINTS - Supernova 1987A INTensive Survey

November 2003 HST image of the SN1987A gaseous ring SN1987A, in the Large Magellanic Cloud, is (as far as we know) the nearest supernova to the Sun since Kepler's supernova of 1604. While its eruption, in January 1987, predated HST's launch by over 3 years, the remnant has been a regular target. Those high resolution observations have revealed the development and evolution of considerable structure, as the blast wave from SN1987A encounters the surrounding interstellar medium. In particular, a striking circum-remnant ring has developed, with numerous hot spots stimulated by the fastest moving debris. This program continues to monitor the development of these features, with series of observations that are co-ordinated with the Chandra X-ray Observatory. During the precent cycle, the hotspots may fuse, as the shock fully enters the ring, and photons from these regions may excite previously hidden gas outside the ring, illuminating mass lost from the progenitor before the explosion. The inner debris are now well resolved, and clearly asymmetrical. Overall, these observations provide crucial insight into the earliest stages of formation of a supernova remnant.

Past weeks:
page by Neill Reid, updated 6/4/2006