This week on HST

HST Programs: October 23 - October 29, 2006

Program Number Principal Investigator Program Title Links
10551 Shri Kulkarni, California Institute of Technology Gamma-Ray Bursts from Start to Finish: A Legacy Approach Abstract
10556 David Turnshek, University of Pittsburgh Neutral Gas at Redshift z=0.5 Abstract
10599 Paul Kalas, University of California - Berkeley Multi-color imaging of two 1 Gyr old debris disks within 20 pc of the Sun: Astrophysical mirrors of our Kuiper Belt Abstract
10607 Ben Sugerman, Space Telescope Science Institute Probing Circumstellar and Interstellar Dust with Scattered-Light Echoes Abstract
10632 Massimo Stiavelli, Space Telescope Science Institute Searching for galaxies at z>6.5 in the Hubble Ultra Deep Field Abstract
10760 Michael Garcia, Smithsonian Institution Astrophysical Observatory Black Hole X-ray Novae in M31 Abstract
10766 Andreas Zezas, Smithsonian Institution Astrophysical Observatory A Deep X-ray Survey of the Small Magellanic Cloud Abstract
10802 Adam Riess, Space Telescope Science Institute SHOES-Supernovae, HO, for the Equation of State of Dark energy Abstract
10816 Tom Brown, Space Telescope Science Institute The Formation History of Andromeda's Extended Metal-Poor Halo 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
10851 Raghvendra Sahai, Jet Propulsion Laboratory Solving the Riddle of the Red Rectangle: Proper Motion Study of a Bipolar Nebula around a Binary Abstract
10867 Robert Kirshner, Harvard University SAINTS - Supernova 1987A INTensive Survey Abstract
10878 John O'Meara, The Pennsylvania State University An ACS Prism Snapshot Survey for z~2 Lyman Limit Systems Abstract
10882 William Sparks, Space Telescope Science Institute Emission Line Snapshots of 3CR Radio Galaxies Abstract
10895 Paul Kalas, University of California - Berkeley Closure on the IRAS Big Four: A High Contrast Study of Epsilon Eridani's Dust Belt in Scattered Light Abstract
10896 Paul Kalas, University of California - Berkeley An Efficient ACS Coronagraphic Survey for Debris Disks around Nearby Stars Abstract
10905 R. Tully, University of Hawaii The Dynamic State of the Dwarf Galaxy Rich Canes Venatici I Region Abstract
10911 John P. Blakeslee, Washington State University Calibration of ACS F814W Surface Brightness Fluctuations Abstract
10989 George Benedict, University of Texas at Austin Astrometric Masses of Extrasolar Planets and Brown Dwarfs Abstract
10996 Holland Ford, The Johns Hopkins University NICMOS J-band Imaging of Strongly Lensing Cluster Abstract
11015 John Hughes, Rutgers the State University of New Jersey The Proper Motion of Supernova Remnant E0509-67.5 Abstract

Some selected highlights

GO 10540: Imaging Nearby Dusty Disks

High-resolution HST image of the face-on debris disk in the G2 dwarf, HD 107146 Planet formation occurs in circumstellar disks around young stars. Most of the gaseous content of those disks dissipates in less than 10 million years, leaving dusty debris disks that are detectable through reflect light at near-infrared and, to a lesser extent, optical wavelengths. The structure of those disks is affected by massive bodies (i.e. planets and asteroids), which, through dynamical interactions and resonances, can produce rings and asymmetries. Analysis of the rangle of morphological structure in these systems provides insight into the distribution of properties of planetary systems. Disk imaging programs have demonstrated that the HST currently provides the only means of achieving the high-contrast required for the detection of these scattered light disks in the presence of the bright parent stars. The present proposal is using NICMOS to image ten nearby F-type dwarfs.

GO 10911: Calibration of ACS F814W Surface Brightness Fluctuations

Simulations of a nearby dwarf galaxy, a nearby giant galaxy and a distant giant galaxy; note that the last is similar in angular size to the dwarf, but has a much smoother brightness distribution (simulations from Ned Wright's ABC of distances The determination of the Cosmic Distance Scale remains one of the major goals of cosmological programs in the early 21st century. Achieving this goal requires a reliable distance indicator. While observing programs continue to pursue conventional primary distance indicators (such as RR Lyraes and Cepheids) and secondary distance indicators (such as the RGB tip and the Tully-Fisher relation), attention is also being given to the method of surface brightness fluctuations. This method rests primarily on the hypothesis that the stellar populations in most galaxies have similar colour-magnitude diagrams. Thus, the total luminosity of the galaxy is generated by similar stars - mainly red giants. In a nearby low-luminosity galaxy, most of the light comes from a relatively small numebr of giant branch stars; consequently, that galaxy has a "grainier" appearance than a distant high-luminosity galaxy of the same apparent magnitude (see figure). The degree of granularity can therefore serve as a distance indicator. The present program will use ACS (F814W filter) to observe half a dozen galaxies in the Fornax cluster to provide a reliable calibration of this technique.

GO 10989: Astrometric masses of extrasolar planets and brown dwarfs

Artist's impression of the planets circling the M dwarf, Gl 876 The overwhelming majority of extrasolar planetary systems have been identified through radial velocity monitoring, and the detection of the reflex motion of the parent star as it orbits the common center of mass of the system. Just as radial velocities measure the stellar "wobble" introduced along the line of sight, so high precision astrometry can be used to measure motion in the plane of the sky. Combining these data gives the full three-dimensional motions of the system, and a direct measure of the mass of the planetary companion. The Fine Guidance Sensors on HST are the only system currently capable of making observations at the required sub-milliarcscond accuracy, and has already been used for astrometry of four systems, including the M dwarf Gl 876. The current GO program pursues observations of six planetary hosts, and FGS observations of HD 33636 are scheduled over the next week.

Past weeks:
page by Neill Reid, updated 20/10/2006