HST this week: 007



This week on HST


HST Programs: January 7 - January 13, 2013

Program Number Principal Investigator Program Title
12109 Julianne Dalcanton, University of Washington A Panchromatic Hubble Andromeda Treasury - I
12113 Julianne Dalcanton, University of Washington A Panchromatic Hubble Andromeda Treasury - I
12114 Julianne Dalcanton, University of Washington A Panchromatic Hubble Andromeda Treasury - I
12442 Sandra M. Faber, University of California - Santa Cruz Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey -- GOODS-North Field, Non-SNe-Searched Visits
12472 Claus Leitherer, Space Telescope Science Institute CCC - The Cosmic Carbon Conundrum
12525 William C. Keel, University of Alabama Giant Ionized Clouds Around Local AGN - Obscuration and History
12555 Robert Louis da Silva, University of California - Santa Cruz On the Triggering of Quasars During First Passage
12568 Matthew A. Malkan, University of California - Los Angeles WFC3 Infrared Spectroscopic Parallel Survey WISP: A Survey of Star Formation Across Cosmic Time
12603 Timothy M. Heckman, The Johns Hopkins University Understanding the Gas Cycle in Galaxies: Probing the Circumgalactic Medium
12787 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12788 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12790 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12870 Boris T. Gaensicke, The University of Warwick The mass and temperature distribution of accreting white dwarfs
12880 Adam Riess, The Johns Hopkins University The Hubble Constant: Completing HST's Legacy with WFC3
12891 Keith S. Noll, NASA Goddard Space Flight Center Search For Binaries Among Ultra-Slow Rotating Trojans, Hildas, and Outer Main Belt Asteroids
12903 Luis C. Ho, Carnegie Institution of Washington The Evolutionary Link Between Type 2 and Type 1 Quasars
12914 Tuan Do, University of Toronto Measuring the Milky Way Mass with the Proper Motion of Leo T
12918 Kristin Chiboucas, Gemini Observatory, Northern Operations Origin of UCDs in the Coma Cluster
12926 Michael Shara, American Museum of Natural History Local Thermonuclear Runaways in Dwarf Novae?
12942 Eilat Glikman, Yale University Testing the Merger Hypothesis for Black Hole/Galaxy Co-Evolution at z~2
12960 Yoshiaki Ono, University of Tokyo, Institute of Cosmic Ray Research The nature of star formation in two spectroscopically confirmed exceptionally-luminous galaxies beyond a redshift 7
12982 Nicolas Lehner, University of Notre Dame Are the Milky Way's High Velocity Clouds Fuel for Star Formation or for the Galactic Corona?
13002 Rik Williams, Carnegie Institution of Washington Monsters at the Dawn of the Thermal Era: Probing the extremes of galactic mass at z>2.5
13003 Michael D. Gladders, University of Chicago Resolving the Star Formation in Distant Galaxies
13007 Lee Armus, California Institute of Technology UV Imaging of Luminous Infrared Galaxies in the GOALS Sample
13023 Marco Chiaberge, Space Telescope Science Institute - ESA Universe in transition: powerful activity in the Bright Ages
13024 John S. Mulchaey, Carnegie Institution of Washington A Public Snapshot Survey of Galaxies Associated with O VI and Ne VIII Absorbers
13032 Carol A. Grady, Eureka Scientific Inc. Crossing the Snow Line: Mapping Ice Photodesorption products in the Disks of Herbig Ae-Fe stars
13050 Remco van den Bosch, Max-Planck-Institut fur Astronomie, Heidelberg The Most Massive Black Holes in Small Galaxies
13058 Kailash C. Sahu, Space Telescope Science Institute Accurate Mass Determination of the Old White Dwarf G105-30 through Astrometric Microlensing
13109 Martin C. Weisskopf, NASA Marshall Space Flight Center Joint Chandra and HST Monitoring and Studies of the Crab Nebula

Selected highlights

GO 12568: WISP - A 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 redshifts 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 12914: Measuring the Milky Way mass with the proper motion of Leo T


SDSS image of the dwarf galaxy, Leo T
As a large spiral galaxy, the Milky Way system includes a number of satellite dwarf galaxies. The most prominent are the two Magellanic Clouds, both gas-rich, star-forming systems, with the LMC essentially a low mass, late-type spiral. Most of the remaining companions are dwarf spheroidals with old, evolved stellar populations and masses that are less than a few x 107 MSun, or less than 10-4 that of the Milky Way. The orbital properties of these systems can be used to constrain the total mass of the Milky Way, and hence gain insight into the overall scale and distribution of its dark matter halo. The more distant the dwarf galaxy, the greater the lever arm on the Milky way's radial mass distribution. Clearly, such measurements requier 3-D space motions; determining radial velocities is a relatively straightforward task, but proper motion measurements are much more challenging. HST has played a crucial role in these investigations, with past observations with ACS of dwarfs such as Cetus, Leo A, Tucana and the Sagittarius Dwarf Irregular (GO program 12273). The present program targets the dwarf system, Leo T, was discovered in 2006 from analysis of data obtained for the Sloan Digital Sky Survey. It lies at a distance of roughly 420 kpc, the most distant of the dwarf galaxies, and may be on its first pass through the system. The present program will use ACS images taken over a 2-year baseline to edtermine proper motions (relative to ackground galaxies) to an accuracy of 0.03 mas/yr.

GO 12880: The Hubble Constant: Completing HST's Legacy with WFC3

A GALEX image of Messier 106 (NGC 4258), one of the galaxies targeted in this program The Hubble constant remains a key parameter in understanding cosmology and the evolution of the Universe. Refining measurements of H0 therefore still represents a vital means of probing the nature of dark energy. The present program aims to tackle this question by laying a firmer foundation to the SNe Ia distance scale. The WFC3 IR camera will be used to identify and characterise Cepheid variables in eight relatively nearby galaxies that have hosted Type Ia SNe. Cepheids have signficantly lower amplitude at near-infrared wavelengths, and the measured magnitudes are less subject to uncertainties due to foreground reddening and variations in metallicity. As a consequence, determining the mean apparent magnitude, and hence the period/apparent magnitude relation, is substantially more straightforward than at optical wavelengths. WFC3 has revolutionised this field by providing substantial greater areal coverage and higher precision photometry than NICMOS. Past observational program have targeted the Cepheids in the maser galaxy, NGC 4258, as well as Galactic Cepheids. The present program targets eight galaxies that have hosted Type Ia supernovae, offering the prospect of tying the SNe Ia scale directly to the Galaxy and to NGC 4258, avoiding the many intermediate steps of previous analyses. The aim is to reduce the level of systematics in determinations of H0 to the 1-2 percent level, setting signficantly stronger constraints on dark energy.

Past weeks:
page by Neill Reid, updated 14/10/2012
These pages are produced and updated on a best effort basis. Consequently, there may be periods when significant lags develop. we apologise in advance for any inconvenience to the reader.