This week on HST


HST Programs: August 24 - August 30, 2015

Program Number Principal Investigator Program Title
13645 Xiaohui Fan, University of Arizona Galactic Environment of A Twenty-Billion Solar-Mass Black Hole at the End of Reionization
13654 Matthew Hayes, Stockholm University Ultraviolet Spectroscopy of the Extended Lyman Alpha Reference Sample
13671 Harald Ebeling, University of Hawaii Beyond MACS: A Snapshot Survey of the Most Massive Clusters of Galaxies at z>0.5
13677 Saul Perlmutter, University of California - Berkeley See Change: Testing time-varying dark energy with z>1 supernovae and their massive cluster hosts
13695 Benne W. Holwerda, Sterrewacht Leiden STarlight Absorption Reduction through a Survey of Multiple Occulting Galaxies (STARSMOG)
13706 Joshua E. G. Peek, Space Telescope Science Institute Galactic Accretion Unveiled: A Unique Opportunity with COS and M33
13710 Philip A. Rosenfield, Harvard University Constraining Models of Evolved UV-Bright Stars in the M31 Bulge
13719 David John Wilson, The University of Warwick Accretion of planetary debris onto the unique white dwarf GD394
13728 Steven Kraemer, Catholic University of America Do QSO2s have Narrow Line Region Outflows? Implications for quasar-mode feedback
13732 Anna Nierenberg, The Ohio State University Detecting dark matter substructure with narrow line lensing
13741 Thaisa Storchi-Bergmann, Universidade Federal do Rio Grande do Sul Constraining the structure of the Narrow-Line Region of nearby QSO2s
13755 Jenny E. Greene, Princeton University The Hosts of Megamaser Disk Galaxies (II)
13760 Derck L. Massa, Space Science Institute Filling the gap --near UV, optical and near IR extinction
13767 Michele Trenti, University of Melbourne Bright Galaxies at Hubble's Detection Frontier: The redshift z~9-10 BoRG pure-parallel survey
13773 Rupali Chandar, University of Toledo H-alpha LEGUS: Unveiling the Interplay Between Stars, Star Clusters, and Ionized Gas
13776 Michael D. Gregg, University of California - Davis Completing The Next Generation Spectral Library
13779 Sangeeta Malhotra, Arizona State University The Faint Infrared Grism Survey (FIGS)
13800 C. Simon Jeffery, Armagh Observatory Heavy-metal, extreme chemistry and puzzling pulsation: ultraviolet clues to the formation of hot subdwarfs
13801 Varsha Kulkarni, University of South Carolina Research Foundation Probing Structure in Cold Gas at z <~ 1 with Gravitationally Lensed Quasar Sightlines
13808 Antonella Nota, Space Telescope Science Institute - ESA Westerlund 2, top to bottom: how massive star clusters form.
13831 Nial R. Tanvir, University of Leicester GRB hosts and the search for missing star formation at high redshift
13857 Julianne Dalcanton, University of Washington Emission Line Stars in Andromeda
13868 Dale D. Kocevski, Colby College Are Compton-Thick AGN the Missing Link Between Mergers and Black Hole Growth?
13875 Gabor Worseck, Max-Planck-Institut fur Astronomie, Heidelberg A Potential Paradigm Shift in our Understanding of Helium Reionization
14045 Imke de Pater, University of California - Berkeley Longitude-resolved maps of Uranus's radio emission
14106 Lorenz Roth, Royal Institute of Technology Probing Ceres' exosphere and water vapor outgassing
14118 Luigi R. Bedin, Osservatorio Astronomico di Padova The end of the White Dwarf Cooling Sequences of Omega Centauri

Selected highlights

GO 13645; Galactic Environment of A Twenty-Billion Solar-Mass Black Hole at the End of Reionization


Artist's impression of an accreting super-mass black hole
Quasars are highly energetic sources that can achieve luminosities substantially exceeding 1012 LSun. These objects are generally believed to be powered by accretion onto a central supermassive black hole, with M > 107 MSun. Many QSOs reside within galaxies that are morphologically similar to elliptical galaxies, which are predominantly gas poor at the present epoch. One of the key research areas in galaxy evolution centres on the formation and growth of the central supermassive black hole and how that growth might have influenced the development of the surronding host galaxy. The present program targets a newly-discovered high-redshift quasar for detailed study. The system, J0010+2802, lies at a redshift of z~6.30 and is approximately ten times more luminous than they typical z~6 QSO. This program will combine ACS i, z and WFC3-IR J, H imaging to identify young, star-formign galaxies in the vicinity of the QSO, and probe the UV emission and star formation in the quasar host.

GO 13831: GRB hosts and the search for missing star formation at high redshift


ACS images of GRB host galaxies
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 identify young galaxies at redshifts 8.2 > z > 6. The WFC3-IR camera is targetting the locations of GRBs that have been either been spectroscopically confirmed at those redshifts or have high photometric redshifts. In each case, the GRB is long gone, so the WFC3-IR F140W imaging should reveal the underlying host galaxy, allowing a determination of its morphology and luminosity.

GO 13677: See Change: Testing time-varying dark energy with z>1 supernovae and their massive cluster hosts


HST/ACS images of a supernova in a galazy at z=1.2
The last few years of the twentieth century saw a revolution in cosmology, with the measurement of the acceleration term in expansion at high redshifts and the identification of dark energy as a major cosmological component. The overall significance of this result has been recognised through the award of the Nobel prize and, most recently, the Fundamental Physics Breakthrough Prize to Perlmutter, Riess and Schmidt and their respective teams. Type Ia supernovae are the prime yardstick for measuring the rate of expansion at moderate and high redshifts. The seminal work in this field was carried out with ground-based telescopes, but Hubble offers almost the only way of obtaining reliable post-maximum photometry of these objects to determine the full shape of the light curve. Many previous HST supernovae programs have concentrated on field galaxies, but applying appropriate corrections for in situ reddening by dust remains an issue in these systems, while the overall SNe detection rates are relatively low at high redshifts. The present program takes a different tack, and aims to minimise the uncertainties by searching for supernovae in massive, high-redshift clusters. The expectation is that the majority of detections lie within dust-poor elliptical galaxies; moreover, supernova rates may be higher. The program will obtain ACS observations of ten of the most massive galaxy clusters lying at redshifts 1.1 < z < 1.75.

GO 14045: Longitude-resolved maps of Uranus's radio emission


The changing aspect of Uranus
Uranus is the nearer of the Solar System's ice giants, following an orbit that takes it between 18.4 and 20.1 AU from the Sun. As such, it has only been visited by one NASA mission, Voyager 2 in January 1986. At that time, the planet appeared almost featureless to both Voyager and ground-based telescopes. That remained the case until 2006, one year before Uranus passed through the equinox, when Hubble observations revealed a dark spot in addition to equatorial bands. The feature is likely an atmospheric storm, with a similar origin to features visible in Jupietr and Saturn. The overall lower activity likely reflects the much lower insolation level, an order of magnitude less than at Jupiter's orbit. There have been several subsequent outbreaks, with both dark and bright spots visible at a range of wavelengths. This has led to speculation that the increased activity might be related to the change in orientation with respect to the Sun: Uranus has an inclination of close to 90 degrees; as it moves through it's 84-year orbit, the orientation changes from pole-on to the Sun, through an equatorial view, to directing the other pole towards the Sun. The present observations aim to combine multi-wavelength imaging of Uranus with HST and radio observations with the VLA in A configuration to probe the wind structrue in the atmosphere, with the aim of understanding the dynamics and the potential for long-term cyclical variations drivn by the inclination.

Past weeks:
page by Neill Reid, updated 11/11/2014
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