This week on HST

HST Programs: March 29, 2010 - April 4, 2010

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
11516 James Green, University of Colorado at Boulder COS-GTO: Cold ISM Abstract
11520 James Green, University of Colorado at Boulder COS-GTO: QSO Absorbers, Galaxies and Large-scale Structures in the Local Universe Abstract
11557 Gabriela Canalizo, University of California - Riverside The Nature of low-ionization BAL QSOs Abstract
11561 Boris T. Gaensicke, The University of Warwick An intensive COS spectroscopic study of the planetary debris disks around two warm white dwarfs 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
11568 Seth Redfield, Wesleyan University A SNAPSHOT Survey of the Local Interstellar Medium: New NUV Observations of Stars with Archived FUV Observations Abstract
11570 Adam Riess, The Johns Hopkins University & Space Telescope Science Institute Narrowing in on the Hubble Constant and Dark Energy Abstract
11583 Joel N. Bregman, University of Michigan The Star Formation Rate In Nearby Elliptical Galaxies Abstract
11591 Jean-Paul Kneib, Laboratoire d'Astrophysique de Marseille Are Low-Luminosity Galaxies Responsible for Cosmic Reionization? Abstract
11592 Nicolas Lehner, University of Notre Dame Testing the Origin(s) of the Highly Ionized High-Velocity Clouds: A Survey of Galactic Halo Stars at z>3 kpc Abstract
11594 John M. O'Meara, Saint Michaels College A WFC3 Grism Survey for Lyman limit absorption at z=2 Abstract
11598 Jason Tumlinson, Space Telescope Science Institute How Galaxies Acquire their Gas: A Map of Multiphase Accretion and Feedback in Gaseous Galaxy Halos Abstract
11599 Richard A. Wade, The Pennsylvania State University Distances of Planetary Nebulae from SNAPshots of Resolved Companions Abstract
11620 William C. Keel, University of Alabama A Quasar Light Echo in the Local Universe? Abstract
11635 Michael Shara, American Museum of Natural History In Search of SNIb/Ic Wolf-Rayet Progenitors and Comparison with Red Supergiants (SNII Progenitors) in the Giant ScI Spiral M101 Abstract
11643 Ann Zabludoff, University of Arizona A Timeline for Early-Type Galaxy Formation: Mapping the Evolution of Star Formation, Globular Clusters, Dust, and Black Hole 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
11650 William M. Grundy, Lowell Observatory Mutual Orbits, Colors, Masses, and Bulk Densities of 3 Cold Classical Transneptunian Binaries Abstract
11661 Misty C. Bentz, University of California - Irvine The Black Hole Mass - Bulge Luminosity Relationship for the Nearest Reverberation-Mapped AGNs Abstract
11662 Misty C. Bentz, University of California - Irvine Improving the Radius-Luminosity Relationship for Broad-Lined AGNs with a New Reverberation Sample Abstract
11663 Mark Brodwin, Harvard University Formation and Evolution of Massive Galaxies in the Richest Environments at 1.5 < z < 2.0 Abstract
11666 Adam J. Burgasser, Massachusetts Institute of Technology Chilly Pairs: A Search for the Latest-type Brown Dwarf Binaries and the Prototype Y Dwarf Abstract
11679 Craig L. Sarazin, The University of Virginia Probing The Globular Cluster / Low Mass X-ray Binary Connection in Early-type Galaxies At Low X-ray Luminositie Abstract
11687 Thomas R. Ayres, University of Colorado at Boulder SNAPing Coronal Iron Abstract
11696 Matthew A. Malkan, University of California - Los Angeles Infrared Survey of Star Formation Across Cosmic Time Abstract 11700 Michele Trenti, University of Colorado at Boulder Bright Galaxies at z>7.5 with a WFC3 Pure Parallel Survey Abstract
11704 Brian Chaboyer, Dartmouth College The Ages of Globular Clusters and the Population II Distance Scale Abstract
11709 David Bersier, Liverpool John Moores University Stretching the diversity of cosmic explosions: The supernovae of gamma-ray bursts Abstract
11715 Howard E. Bond, Space Telescope Science Institute The Luminous Galactic Cepheid RS Puppis: A Geometric Distance from its Nested Light Echoes Abstract
11732 C. S. Kochanek, The Ohio State University Research Foundation The Temperature Profiles of Quasar Accretion Disks Abstract
11736 David M. Meyer, Northwestern University The Nearest Cold Interstellar Cloud Abstract
11786 Howard E. Bond, Space Telescope Science Institute HST Observations of Astrophysically Important Visual Binaries Abstract
11789 George Fritz Benedict, University of Texas at Austin An Astrometric Calibration of Population II Distance Indicators Abstract
11802 Holland Ford, The Johns Hopkins University WFC3/IR Observations of Strongly Lensing Clusters Abstract

Selected highlights

GO 11650: Orbits, Masses, and Densities of Three Cold Classical Transneptunian Binaries

Preliminary orbital determination for the KBO WW31, based on C. Veillet's analysis of CFHT observations; the linked image shows the improved orbital derivation, following the addition of HST imaging The Kuiper Belt consists of icy planetoids that orbit the Sun within a broad band stretching from Neptune's orbit (~30 AU) to distance sof ~50 AU from the Sun (see David Jewitt's Kuiper Belt page for details). Over 500 KBOs (or trans-Neptunian objects, TNOs) are currently known out of a population of perhaps 70,000 objects with diameters exceeding 100 km. Approximately 2% of the known KBOs are binary (including Pluto, one of the largest known KBOs, regardless of whether one considers it a planet or not). This is a surprisingly high fraction, given the difficulties involved in forming such systems and the relative ease with which they can be disrupted. It remains unclear whether these systems formed from single KBOs (through collisions or 3-body interactions) as the Kuiper Belt and the Solar System have evolved, or whether they represent the final tail of an initial (much larger) population of primordial binaries. These issues can be addressed, at least in part, through deriving a better understanding of the composition of KBOs - and those properties can be deduced by measuring the orbital parameters for binary systems. The present proposal aims to use HST WFC3 observations to map the orbits of three binary systems. Those observations will be ued to determine the orbital period and semi-major axis and the total system mass, while the mid-infrared properties (measured by Spitzer) allow an assessment of the surface area/diameters; combining these measurements gives an estimate of the mean density.

GO 11696: Infrared Survey of Star Formation Across Cosmic Time

A region of massive star formation Star formation is the key astrophysical process in determining the overall evolution of galactic systems, the generation of heavy elements, and the overall enrichment of interstellar and intergalactic material. Tracing the overall evolution through a wide redshift range is crucial to understanding how gas and stars evolved to form the galaxies that we see around us now. The present program builds on the ability of HST to carry out parallel observations, using more than one instrument. While the Cosmic Origins Spectrograph is focused on obtaining ultraviolet spectra of unparalleled signal-to-noise, this program uses the near-infrared grisms mounted on the Wide-Field Camera 3 infrared channel to obtain low resolution spectra between 1 and 1.6 microns of randomly-selected nearby fields. The goal is to search for emission lines characteristic of star-forming regions. In particular, these observations are capable of detecting Lyman-alpha emission generated by star formation at redshfits z > 5.6. A total of up to 40 "deep" (4-5 orbit) and 20 "shallow" (2-3 orbit) fields will be targeted in the course of this observing campaign.

GO 11715: The Luminous Galactic Cepheid RS Puppis: A Geometric Distance from its Nested Light Echoes

ESO image of the material surrounding the Cepheid, RS Puppis RS Puppis is a 6th magnitude star that lies within the poop deck of the old, southern constellation, Argo Navis. It is a Cepheid variable with a period of 41.4 days, a relatively long period that is comparable with many that serve as standard candles for the extragalactic distance scale. It also has the distinction of being the only such variable embedded within extended nebulosity. The surrounding nebulosity reflects the light from parent star, and therefore goes variations in brightness that track the stellar variability cycle - with a lag that depends on the distance between star and dust. The angular size of the reflecting nebulosity can be measured directly, so if the light travel time star --> dust can be determined, then we can determine an absolute distance to the variable, and hence place a very well calibrated point on the Cepheid PLC. Those observations have been made from the ground, but there is an ambiguity in matching cycle counts to distance that can only be dealt with by assuming that the features lie in the plane of the sky. This proposal aims to circumvent that problem by using polarimetry to determine the extent of any foreground/background projection.

GO 11789: An Astrometric Calibration of Population II Distance Indicators

Measuring trigonometric parallax Trigonometric parallax measurement remains the fundamental method of determining distances to astronomical objects. The best ground-based parallax measurements can achieve accuracies of ~1 milliarcsecond, comparable with the typical accuracies achieved by the ESA Hipparcos astrometric satellite. This level of accuracy allows us to obtain reliable distances and luminosities for main sequence stars, subgiants, red giants and even a number of metal poor subdwarfs. However, with an effective distance limit of 100-150 parsecs, the sampling volume includes less than a handful of rarer, shorter-lived celestial objects. In particular, there are no RR Lyraes or Cepheids, two of the principal calibrators in the extragalactic distance scale. There is only one instrument currently available that can achieve astrometry of higher accuracy - the Fine Guidance Sensors (FGS) on HST. The present team used the FGS to measure a parallax of 3.82+/10.2 milliarseconds for RR Lyrae, the nearest star of its type. this corresponds to a distance of 262 parsecs. The present program aims to improve the calibration by extending observations to four more relatively nearby RR Lyraes (XZ Cyg, UV Oct, RZ Cep and SU Dra) and two Pop II Cepheids (Kappa Pav and VY Pyx).

Past weeks:
page by Neill Reid, updated 19/2/2010