This week on HST

HST Programs: July 4, 2010 - July 10, 2010

Program Number Principal Investigator Program Title
11149 Eiichi Egami, University of Arizona Characterizing the Stellar Populations in Lyman-Alpha Emitters and Lyman Break Galaxies at 5.7
11202 Leon Koopmans, Kapteyn Astronomical Institute The Structure of Early-type Galaxies: 0.1-100 Effective Radii
11219 Alessandro Capetti, Osservatorio Astronomico di Torino Active Galactic Nuclei in nearby galaxies: a new view of the origin of the radio-loud radio-quiet dichotomy?
11235 Jason A. Surace, California Institute of Technology HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies in the Local Universe
11360 Robert W. O'Connell, The University of Virginia Star Formation in Nearby Galaxies
11556 Marc W. Buie, Southwest Research Institute Investigations of the Pluto System
11557 Gabriela Canalizo, University of California - Riverside The Nature of low-ionization BAL QSOs
11588 Raphael Gavazzi, CNRS, Institut d'Astrophysique de Paris Galaxy-Scale Strong Lenses from the CFHTLS survey
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
11594 John M. O'Meara, Saint Michaels College A WFC3 Grism Survey for Lyman limit absorption at z=2
11598 Jason Tumlinson, Space Telescope Science Institute How Galaxies Acquire their Gas: A Map of Multiphase Accretion and Feedback in Gaseous Galaxy Halos
11626 Philip Massey, Lowell Observatory Searching for the Upper Mass Limit in NGC 3603, the Nearest Giant H II Region
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
11648 Emanuele Daddi, Commissariat a l'Energie Atomique (CEA) WFC3 spectroscopy of an X-ray luminous galaxy cluster at z>2
11658 David A. Turnshek, University of Pittsburgh Probing the Outer Regions of M31 with QSO Absorption Lines
11661 Misty C. Bentz, University of California - Irvine The Black Hole Mass - Bulge Luminosity Relationship for the Nearest Reverberation-Mapped AGNs
11663 Mark Brodwin, Smithsonian Institution Astrophysical Observatory Formation and Evolution of Massive Galaxies in the Richest Environments at 1.5 < z < 2.0
11680 Graeme H. Smith, University of California - Santa Cruz The Main Sequence Luminosity Function of Low-Mass Globular Clusters
11684 Roeland van der Marel, Space Telescope Science Institute The First Proper Motion Measurement for M31: Dynamics and Mass of the Local Group
11686 Nahum Arav, Virginia Polytechnic Institute and State University The Cosmological Impact of AGN Outflows: Measuring Absolute Abundances and Kinetic Luminosities
11694 David R. Law, University of California - Los Angeles Mapping the Interaction between High-Redshift Galaxies and the Intergalactic Environment
11696 Matthew A. Malkan, University of California - Los Angeles Infrared Survey of Star Formation Across Cosmic Time
11697 Slawomir Stanislaw Piatek, New Jersey Institute of Technology Proper Motion Survey of Classical and SDSS Local Group Dwarf Galaxies
11710 John P. Blakeslee, Dominion Astrophysical Observatory The Extreme Globular Cluster System of Abell 1689: The Ultimate Test of Universal Formation Efficiency
11727 Timothy M. Heckman, The Johns Hopkins University UV spectroscopy of Local Lyman Break Galaxy Analogs: New Clues to Galaxy Formation in the Early Universe
11732 C. S. Kochanek, The Ohio State University Research Foundation The Temperature Profiles of Quasar Accretion Disks
11831 Preeti Kharb, Rochester Institute of Technology Probing X-Ray Jet Emission Mechanisms in a Complete Blazar Sample

Selected highlights

GO 11360: Star Formation in Nearby Galaxies

WFC3 image of star forming regions in M83 Star formation remains a (perhaps "the") key astrophysical process in determining the overall evolution of galactic systems. Wide Field Camera 3, the new imaging camera installed in HST during Servicing Mission 4, has two channels, semsitive to UVIS and IR wavelengths respectively, each equipped with a wide range of filters, sampling broad- and narrow-band wavelengths ranges from 2000 Angstroms to 1.7 microns. This panchromatic capability, coupled with the availability of the Advanced Camera for Surveys at visual and red wavelengths, is being being applied to survey active star forming regions in a number of nearby galaxies. The targets include M85, NGC 4150, 30 Doradus in the Large Magellanic Cloud, Centaurus A (NGC 5128) and (pictured above) M83.

GO 11592: Testing the Origin(s) of the Highly Ionized High-Velocity Clouds: A Survey of Galactic Halo Stars at z>3 kpc

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. The present program aims to use distant halo stars to probe a subset of the known HVCs within the Milky Way.

GO 11644: A dynamical-compositional survey of the Kuiper belt: a new window into the formation of the outer solar system

The architecture of the outer Solar System The Kuiper Belt lies beyond the orbit of Neptune, extending from ~30 AU to ~50 AU from the Sun, and includes at least 70,000 objects with diameters exceeding 100 km. Setting aside Pluto, the first trans-Neptunian objects were discovered in the early 1990s. Most are relatively modest in size, with diameters of a few hundred km and photometric properties that suggested an icy composition, similar to Pluto and its main satellite, Charon. Over the last three years, a handful of substantially larger bodies have been discovered, with diameters of more than 1000 km; one of the objects, 2003 UB313, is comparable in size to Pluto (2320 km.). At the same time, ground-based surveys, such as the Deep Ecliptic Survey, the Canada-France Ecliptic plane Survey and the Palomar Quest Survey, scanned the ecliptic for fainter, lower-mass objects, with the aim of using their properties to assess the likely chemical composition and dynamical history of the early Solar System. The present program will use Wide Field Camera 3 to push up to 2 magnitudes fainter than these ground-based studies, providing reliable estimates of compositions for a representative sample of KBOs.

GO 11684: The First Proper Motion Measurement for M31: Dynamics and Mass of the Local Group

A deep HST image of a field in the inner halo of M31; an M31 globular lies at the lower edge of the frame M31 and the Milky Way are the two largest members of the Local Group, with masses of ~4 x 1011 and ~1011 MSun, respectively. As such, they dominate the system dynamics - the M33 and the LMC are the next largest systems, with masses lower by a factor of 10. Radial velocity measurement show that M31 and the Milky Way are converging at a velocity of ~125 km/sec, but determing the relative orbit of the pair requires measurement of motion tangential to the line of sight. In principle, the tangential motion can be determined through astrometry of stars within M31, using background galaxies or quasars to set the reference frame. However, at a distance of ~800 kpc, a tangential velocity of 100 km/sec corresponds to an annual proper motion of only 0.02 milliarcseconds, so acquiring such measurements sets great demands on the observations. The present progam aims to reach those limits by obtaining deep, second epoch ACS and WFC3 images of fields in M31 that were surveyed over 5 years ago using ACS and WFPC2. Background galaxies will provide the reference frame.

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