This week on HST


HST Programs: October 25, 2010 - October 31, 2010

Program Number Principal Investigator Program Title
11189 Nial R. Tanvir, University of Leicester Probing the early universe with GRBs
11524 James C. Green, University of Colorado at Boulder COS-GTO: WARM AND HOT ISM IN AND NEAR THE MILKY WAY
11536 James C. Green, University of Colorado at Boulder COS-GTO: Sleuthing the Source of Distant Cometary Activity
11540 James C. Green, University of Colorado at Boulder COS-GTO: Search for Hydrocarbons and Nitriles in Pluto's Atmosphere
11575 Schuyler D. Van Dyk, Jet Propulsion Laboratory The Stellar Origins of Supernovae
11605 Travis Stuart Barman, Lowell Observatory Obtaining the Missing Links in the Test of Very Low Mass Evolutionary Models with HST
11626 Philip Massey, Lowell Observatory Searching for the Upper Mass Limit in NGC 3603, the Nearest Giant H II Region
11634 Carmen Sanchez Contreras, Instituto de Estructura de la Materia Probing the collimation of pristine post-AGB jets with STIS
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
11721 Richard S. Ellis, California Institute of Technology Verifying the Utility of Type Ia Supernovae as Cosmological Probes: Evolution and Dispersion in the Ultraviolet Spectra
11734 Andrew J. Levan, The University of Warwick The hosts of high redshift gamma-ray bursts
12013 Michael Corcoran, NASA Goddard Space Flight Center Monitoring Dynamical Mass Loss from Eta Car with the HETG
12018 Andrea H. Prestwich, Smithsonian Institution Astrophysical Observatory Ultra-Luminous x-Ray Sources in the Most Metal-Poor Galaxies
12032 James C. Green, University of Colorado at Boulder COS-GTO: An absorption study of galactic intermediate velocity clouds using hot stars in globular clusters - Part 2
12038 James C. Green, University of Colorado at Boulder COS-GTO: COOL, WARM AND HOT GAS IN THE COSMIC WEB AND IN GALAXY HALOS Part 2
12061 Sandra M. Faber, University of California - Santa Cruz Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey -- GOODS-South Field, Early Visits of SNe Search
12099 Adam Riess, The Johns Hopkins University Supernova Follow-up for MCT
12163 Aaron J. Barth, University of California - Irvine Structure and Stellar Content of the Nearest Nuclear Clusters in Late-Type Spiral Galaxies
12167 Marijn Franx, Universiteit Leiden Resolving the Matter of Massive Quiescent Galaxies at z=1.5-2
12184 Xiaohui Fan, University of Arizona A SNAP Survey for Gravitational Lenses Among z~6 Quasars
12210 Adam S. Bolton, University of Utah SLACS for the Masses: Extending Strong Lensing to Lower Masses and Smaller Radii
12212 D. Michael Crenshaw, Georgia State University Research Foundation What are the Locations and Kinematics of Mass Outflows in AGN?
12215 Nancy R. Evans, Smithsonian Institution Astrophysical Observatory Searching for the Missing Low-Mass Companions of Massive Stars
12229 Linda J. Smith, Space Telescope Science Institute HST U-band Survey of Star Clusters in Nearby Star-Forming Galaxies
12272 Christy A. Tremonti, University of Wisconsin - Madison Testing Feedback: Morphologies of Extreme Post-starburst Galaxies
12275 Bart P. Wakker, University of Wisconsin - Madison Measuring gas flow rates in the Milky Way
12286 Hao-Jing Yan, The Ohio State University Hubble Infrared Pure Parallel Imaging Extragalactic Survey {HIPPIES}
12289 J. Christopher Howk, University of Notre Dame A COS Snapshot Survey for z < 1.25 Lyman Limit Systems
12291 John Krist, Jet Propulsion Laboratory STIS coronagraphy of Spitzer-selected debris disks
12298 Richard S. Ellis, California Institute of Technology Towards a Physical Understanding of the Diversity of Type Ia Supernovae
12300 Robert A. Fesen, Dartmouth College A Deep Kinematic Investigation of Cas A's Opposing High-Velocity Ejecta Jets
12302 Edward F. Guinan, Villanova University Probing the Atmospheres of Cepheids with HST-COS: Pulsation Dependences, Plasma Dynamics and Heating Mechanisms
12307 Andrew J. Levan, The University of Warwick A public SNAPSHOT survey of gamma-ray burst host galaxies
12316 John P. Wisniewski, University of Washington HST/FGS Astrometric Search for Young Planets Around Beta Pic and AU Mic
12320 Brian Chaboyer, Dartmouth College The Ages of Globular Clusters and the Population II Distance Scale
12322 Kailash Sahu, Space Telescope Science Institute Detecting Isolated Black Holes through Astrometric Microlensing
12328 Pieter van Dokkum, Yale University 3D-HST: A Spectroscopic Galaxy Evolution Treasury Part 2

Selected highlights

GO 11189: Probing the early universe with GRBs

Artist's impression of a gamma-ray burst Gamma ray bursts are events that tap extraordinary energies (1045 to 1047 joules) in remarkably short periods of time. Several thousands bursts have been detected over the last 30+ years, and analyses indicate that they can be divided into two classes with durations longer or shorter than 2 seconds. The short bursts appear to release more high energy radiation, so the two subsets are known as long/soft and short/hard bursts.The short/hard bursts appear to arise from coalescing binary systems (probably pairs of neutron stars or black holes), but the long/soft bursts appear to originate in the collapse of very massive stars. The latter sources are therefore almost certainly associated with star formation, so they act as signposts to active star-forming regions in the high redshift universe. This program aims to use GRBs to zero in on young galaxies at redshifts z > 6. The WFC3-IR camera is targetting the locations of GRBs that have been either been spectroscopically confirmed at those redshifts (GRB 080913, z=6.7; GRB 090423, z=8.3) or have high photometric redshifts (GRB 0900429B, z~8). In each case, the GRB is long gone, so the WFC3-IR imaging will reveal the underlying host galaxy, allowing a determination of its morphology and luminosity. The present observations target GRB 090423.

GO 11721: Verifying the Utility of Type Ia Supernovae as Cosmological Probes: Evolution and Dispersion in the Ultraviolet Spectra

Recent supernova in M100 Supernovae are the most spectacular form of stellar obituary. In recent years, these celestial explosions have acquired even more significance through the use of Type Ia supernovae as distance indicators in mapping the `dark energy' acceleration term of cosmic expansion. However, while there are well-established models for the two main types of supernovae (runaway fusion on the surface of a white dwarf in a binary system for Type Ia, or detonation of the core in Type II), some uncertainties remain as to the uniformity of the events. Consequently, there is potential for systematic bias in the distance estimates. One of the questionmarks comes from spectroscopy of a number of supernovae at intermediate redshift (z~0.5) that appears to show a substantial dispersion in properties at UV wavelengths. The present program aims to probe this issue by using STIS to obtain UV spectra of nearby supernovae, and therefore examining the detailed behaviour in the local universe.

GO 12275: Measuring gas flow rates in the Milky Way

A map of the high velocity cloud systems surrounding the Milky Way (B. Wakker, U. Wisconsin). The stellar components of the Milky Way Galaxy are well known: the disk, the central bulge and the old, metal-poor stellar halo. However, the Milky Way is also surrounded by a halo of hot, gas that is itself embedded within a much more tenuous corona of even hotter, ionised gas. Within that structure lie high velocity clouds. Originally discovered in the 1930s as absorption features in stellar spectra, these clouds have velocities that differ significantly from the rotational velocity along that line of sight, and they are generally believed to be undergoing infall into the Galaxy. The origin and nature of these systems remains uncertain, with some favouring a Galactic origin, driven by star formation and feedback between disk and halo, and others supporting their origin within the warm-hot intergalactic medium. HVCs are not self luminous, so indirect methods need to be applied to examine their characteristics. The most effective is to identify stars that lie behind individual systems and, as with their discovery in the 1930s, search the stellar spectra for signature absorption lines produced by material within the cloud. Many, indeed most, of the key absorption features lie at ultraviolet wavelengths, a spectral region that has been opened up with the installation of the Cosmic Origins Spectrograph on HST. Detailed information is currently available for only five HVCs. The present program is using active galactic nuclei (AGNs) as background light sources to probe most of the remaining known HVCs within the Milky Way.

GO 12316: HST/FGS Astrometric Search for Young Planets Around Beta Pic and AU Mic

The extended disk around the M dwarf, AU Mic 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 disk structure is affected by massive bodies (i.e. planets and asteroids), which, through dynamical interactions and resonances, can produce rings and asymmetries. Two of the most prominent and best characterised disks are those acompanying the A-type star Beta Pictoris, and the nearby (d~10 parsec) early-type M dwarf, AU Mic. Both stars are young, with age estimates ranging from 8 to 20 million years for beta Pic and 5 to 10 million years for AU Mic. beta Pic's disk, in particular, shows evidence for significant sub-structure that has been attributed to planetary companions. The present HST program aims to use the Fine Guidance Sensors to obtain high precision astrometry of these two young stars, and search for systematic astrometric residuals due to the hypothesised planetary companions. Upcoming observations focus primarily on AU Mic.

Past weeks:
page by Neill Reid, updated 12/8/2010