This week on HST


HST Programs: March 17 - March 23, 2014

Program Number Principal Investigator Program Title
12870 Boris T. Gaensicke, The University of Warwick The mass and temperature distribution of accreting white dwarfs
12902 Matthew A. Malkan, University of California - Los Angeles WFC3 Infrared Spectroscopic Parallel Survey WISP: A Survey of Star Formation Across Cosmic Time
12903 Luis C. Ho, Carnegie Institution of Washington The Evolutionary Link Between Type 2 and Type 1 Quasars
12995 Christopher Johns-Krull, Rice University Testing Disk Locking in the Orion Nebula Cluster
13306 Gillian Wilson, University of California - Riverside Is the Size Evolution of Massive Galaxies Accelerated in Cluster Environments?
13309 Yicheng Guo, University of California - Santa Cruz UV Snapshot of Low-redshift Massive Star-forming Galaxies: Searching for the Analogs of High-redshift Clumpy Galaxies
13330 Bradley M Peterson, The Ohio State University Mapping the AGN Broad Line Region by Reverberation
13331 Laurent Pueyo, Space Telescope Science Institute Confirmation and characterization of young planetary companions hidden in the HST NICMOS archive
13346 Thomas R. Ayres, University of Colorado at Boulder Advanced Spectral Library II: Hot Stars
13351 Saurabh W. Jha, Rutgers the State University of New Jersey UV Spectroscopy of a Peculiar White Dwarf Supernova
13352 Matthew A. Malkan, University of California - Los Angeles WFC3 Infrared Spectroscopic Parallel Survey WISP: A Survey of Star Formation Across Cosmic Time
13361 William P. Blair, The Johns Hopkins University Discovering and Characterizing the Young Supernova Remnant Population in M101
13364 Daniela Calzetti, University of Massachusetts - Amherst LEGUS: Legacy ExtraGalactic UV Survey
13366 Roelof S. de Jong, Astrophysikalisches Institut Potsdam The vertical disk structure of spiral galaxies and the origin of their thick disks
13367 Megan Donahue, Michigan State University UV Line Emission from Million Degree Gas in a Galaxy Cluster Core
13369 Nancy R. Evans, Smithsonian Institution Astrophysical Observatory The Dynamical Mass of Polaris, the Nearest Cepheid
13397 Luciana C. Bianchi, The Johns Hopkins University Understanding post-AGB Evolution: Snapshot UV spectroscopy of Hot White Dwarfs
13404 William M. Grundy, Lowell Observatory Mutual Orbits and Physical Properties of Binary Transneptunian Objects
13412 Tim Schrabback, Universitat Bonn, Argelander Institute for Astronomy An ACS Snapshot Survey of the Most Massive Distant Galaxy Clusters in the South Pole Telescope Sunyaev-Zel'dovich Survey
13415 David Syphers, University of Colorado at Boulder The First Study of the Quasar Broad Line Region in the <550A Extreme UV
13420 Guillermo Barro, University of California - Santa Cruz The progenitors of quiescent galaxies at z~2: precision ages and star-formation histories from WFC3/IR spectroscopy
13444 Bart P. Wakker, University of Wisconsin - Madison Constraining the size of intergalactic clouds with QSO pairs
13483 Goeran Oestlin, Stockholm University eLARS - extending the Lyman Alpha Reference Sample
13488 Andrew J. Steffl, Southwest Research Institute Using Hubble to Resolve Fundamental Discrepancies in the Surface Composition of the Asteroid {21} Lutetia
13490 Jason A. Surace, California Institute of Technology Resolving the Reddest Extragalactic Sources Discovered by Spitzer: Strange Dust-Enshrouded Objects at z~2-3?
13614 Joaquin Vieira, University of Illinois at Urbana - Champaign High-Redshift Starburst Galaxies Under the Cosmic Microscope: Unveiling the stellar histories of strongly lensed starburst galaxies
13620 William B. Sparks, Space Telescope Science Institute Probing the atmosphere of a transiting ocean world: are there ice fountains on Europa?

Selected highlights

GO 12902, 13352: 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 13364: LEGUS: Legacy ExtraGalactic UV Survey


UGC 4305 = Holmberg II - Arp 268, one of the star-forming galaxies targeted by LEGUS
Understanding the global architecture of star formation is a key step towards understanding the morphological evolution of galaxies and the characteristics of the underlying stellar populations. HST has devoted extensive resources to observations of nearby galaxies over its lifetime, including detailed surveys of a handful of systems, notably the PHAT survey of M31, with the enhanced imaging capabilities made available following SM4. Most programs, however, have focused on optical, far-red and, to a lesser extent, near-infrared wavelengths. While those observations provide high-quality colour-magnitude data that enable an exploration of relatively mature populations, they are less effective at probing active star-formation sites populated by young, high-mass stars. Those regions are most prominent at ultraviolet wavelengths, and the present program aims to capitalise on the past heritage of HST observations by adding near-UV imaging for 50 nearby galaxies. The 50 targets are drawn from a catalogue of 400 systems within ~11 Mpc of the Milky Way, and have been selected to provide a fair sampling of the wide variety of galactic systems within that volume. The program will image star-forming regions in these systems in near-UV and blue wavelengths using the WFC3 UVIS channel with the F275W, F336W and F438W filters, supplemented by F55W and F814W (V and I) where necessary.

GO 13366: The vertical disk structure of spiral galaxies and the origin of their thick disks



Ground-based imaging of the edge-on spiral, NGC 891
The stars in the Milky Way are generally grouped into stellar populations, building blocks that provide insight into the process of galaxy assembly. The traditional populations are the near-spherical, metal-poor Halo, representing the first significant burst of star formation; the Disk, whose constituents have higher metallicities, a flattened density distribution (which defines the Galactic Plane) and significant angular momentum, suggesting a formation history that includes collapse and dissipation; and the central Bulge, which, with a spheroidal distribution and broad metallicity range, may be something of an amalgam of disk and halo. The original models for the Disk envisaged a relatively simple population, with a continuous star formation history and an exponential density distribution, both radially and perpendicular to the Plane. However, in the mid-1980s, starcount analyses revealed more complexity in the vertical density distribution, with evidence for two components with scaleheights ~300 and 1000-1300 pc. The extended component is clearly old (>9 Gyrs in age). A variety of emchanisms have been proposed for its formation, dubbed the thick disk, including dynamical scattering within the early disk, formation in situ, or perturbations as the result of major or minor mergers. Ground and space-based observations show that other spiral galaxies possess a similar component. Clearly, the frequency of such systems and their age distribution offer clues to the merging history of the average spiral galaxy. The present program will use ACS and WFC3 to image three massive edge-on spirals at several locations perpendicular to the Plane, with the aim of resolving the underlying stellar populations and tracing the metallicity distribution and overall morphology of the extended disk components.

GO 13488: Using Hubble to Resolve Fundamental Discrepancies in the Surface Composition of the Asteroid {21} Lutetia

A comparison between fly-by images of the asteroid Gaspra and the two martian satellites, Phobos (lower) and Deimos (upper) ESA's Rosetta mission aims to make the first ever landing on a cometary nucleus. As such, it is a follow-up to the Giotto mission, which encountered, imaged and was sand-blasted by Comet Halley during the latter's 1986 perihelion passage. Rosetta was launched on 2 March 2004, and will rendezvous with Comet 67P/Churyumov-Gerasimenko in early 2014. After an extensive period of mapping the comet, Rosetta will release the lander, named Philae (the island in the Nile river where the Rosetta stone was found), which will land on the comet's surface and transmit back data on the chemical composition. On its way to Comet 67P/Churyumov-Gerasimenko, Rosetta made a number of fly-bys of Earth and Mars, boosting the orbital energy, and encountered two asteroids: 2867 Steins (September 5, 2008) and 21 Lutetia (July 10, 2010). Lutetia is a main-belt asteroid with an estimated diameter of 100 kilometres and a potentially unusual composition: although classified as a metallic (type M) asteroid, the spectral characteristics are somewhat unusual. During the fly-by, Rosetta returned information on the spectral energy distribution; however, the data are almost featureless, with no evidence for substantial absorption features, save possibly a significant absorption edge at ~1706 Angstroms. This leaves the overall question of Lutetia's composition unanswered. The present set of Hubble observations aimes to address this question by adding near-UV and far-UV spectroscopy by STIS, probing the UV spectral energy distribution and testing the mnature of the possible absorption feature.

Past weeks:
page by Neill Reid, updated 7/2/2014
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.