This week on HST

HST Programs: September 14 - September 20, 2015

Program Number Principal Investigator Program Title
13655 Matthew Hayes, Stockholm University How Lyman alpha bites/beats the dust
13658 Seth Redfield, Wesleyan University Farewell to the Voyagers: Measuring the Local ISM in the Immediate Path of the Two Voyager Spacecraft
13667 Marc W. Buie, Southwest Research Institute Observations of the Pluto System During the New Horizons Encounter Epoch
13671 Harald Ebeling, University of Hawaii Beyond MACS: A Snapshot Survey of the Most Massive Clusters of Galaxies at z>0.5
13676 Eileen T Meyer, University of Maryland Baltimore County Solving the X-ray Origin Problem in Kiloparsec-Scale Relativistic Jets: Hubble Provides the Missing Key
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)
13729 Andy Lawrence, University of Edinburgh, Institute for Astronomy Slow-blue PanSTARRS transients : high amplification microlens events?
13732 Anna Nierenberg, The Ohio State University Detecting dark matter substructure with narrow line lensing
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
13769 Klaus Werner, Eberhard Karls Universitat, Tubingen Trans-iron group elements in hot helium-rich white dwarfs
13774 Sara Ellison, University of Victoria Feeding and feeback: The impact of AGN on the circumgalactic medium.
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)
13786 Glenn Schneider, University of Arizona Decoding Debris System Substructures: Imprints of Planets/Planetesimals and Signatures of Extrinsic Influences on Material in Ring-Like Disks
13789 Andrea Mehner, European Southern Observatory - Chile Essential UV Observations of Eta Carinae's Change of State
13823 Raphael Gobat, KIAS A complete census of galaxy activity in a massive z>1.5 cluster: probing the SF-density relation down to the low M* regime
13828 Steve Shore, Universita di Pisa Late nebular stage high resolution UV spectroscopy of classical Galactic novae: a benchmark panchromatic archive for nova evolution
13833 Nicolas Tejos, University of California - Santa Cruz Characterizing the cool and warm-hot intergalactic medium in clusters at z < 0.4
13845 Adam Muzzin, University of Cambridge Resolved H-alpha Maps of Star-forming Galaxies in Distant Clusters: Towards a Physical Model of Satellite Galaxy Quenching
13846 Todd Tripp, University of Massachusetts - Amherst The COS Absorption Survey of Baryon Harbors (CASBaH): Probing the Circumgalactic Media of Galaxies from z = 0 to z = 1.5
13862 Timothy M. Heckman, The Johns Hopkins University Measuring the Impact of Starbursts on the Circum-Galactic Medium
13872 Pascal Oesch, Yale University The GOODS UV Legacy Fields: A Full Census of Faint Star-Forming Galaxies at z~0.5-2
13875 Gabor Worseck, Max-Planck-Institut fur Astronomie, Heidelberg A Potential Paradigm Shift in our Understanding of Helium Reionization
13937 Amy Simon, NASA Goddard Space Flight Center Hubble 2020: Outer Planet Atmospheres Legacy (OPAL) Program
13946 Roopesh Ojha, NASA Goddard Space Flight Center The very unusual gamma-ray source PMNJ1603-4904 and its neighbors
14062 Adam Riess, The Johns Hopkins University The Fifth and Final Epoch
14125 Matthew James Darnley, Liverpool John Moores University A Remarkable Recurrent Nova in M31: The Leading Single Degenerate Supernova Ia Progenitor Candidate(?)
14135 Gordon T. Richards, Drexel University Are High-Redshift Spectroscopic Black Hole Mass Estimates Biased?
14136 Bruno Sicardy, Observatoire de Paris Search for material around Chiron
14241 Daniel Apai, University of Arizona Cloud Atlas: Vertical Cloud Structure and Gravity in Exoplanet and Brown Dwarf Atmospheres

Selected highlights

GO 13658: Farewell to the Voayagers: Measuring the Local ISM in the Immediate Path of the Two Voyager Spacecraft

The Voyager spacecraft
The Voyager spacecraft were launched in 1977 as NASA's first reconnaissance mission of the outer solar system. Taking advantage of gravitational assists provided by planetary alignments, Voyager 2, launched in August 1977, conducted fly-bys of Jupiter (July 1979), Saturn (August 1981), Uranus (january 1986) and Neptune (August 1989); Voyager 1, launched in September 1977, only conducted fly-bys of Jupiter (March 1979) and Saturn/Titan (November 1980), but it achieved substantially higher velocities than Voyager 1. Both probes are now headed into the outermost regions of the solar system, with Voyager 2 currently at 108 AU and Voyager 1 at ~132 AU. In August 2012, Voyager 1 crossed the heliopause at ~122 AU, the boundary between the region dominated by the solar wind and outer space. Voyager 2 will reach similar distances in the next few years. Both spacecraft continue to transmit information regarding the local environment - the heliopause transition was marked by a substantial decline in the detection of solar wind particles. The present HST proposal aims to provide complementary information to these is situ measurments by using the Space Telscope Imaging Spectrograph to obtain spectra of 4 stars close to the Voyager sight-lines, 2 for each Voyager. Those spectra will be used to search for absorption features, probing the composition and density of the lcoal interstellar medium.

GO 13676: Solving the X-ray Origin Problem in Kiloparsec-Scale Relativistic Jets: Hubble Provides the Missing Key

Hubble Faint Object Camera image of the jet associated with the quasar 3C 273
Highly collimated jets are common features of active galactic nuclei and quasars. The jets are generally believed to be generated by accretion onto a central supermassive black hole, with the collimation imposed by relativistic beaming. The jets can show extensive structure, as the high velocity material interacts with gas in the intergalactic medium. The present program aims to use Hubble to image the detailed structure of jets in four quasars, ranging in redshift from z=0.06 (4C00.58) to z=3.89 (4C62.29). Chandra observations show that all four have hard x-ray spectra, which is generally interpreted as due to inverse compton scattering of cosmic microwave background photons. However, this mechanism implies that there should be strong gamma ray radiation, which has not been detected. The Hubble observations, obtained with the Advanced Camera for Surveys in the red (F606W filter) and with the Wide-Field Camera 3 IR camera in the near-infrared (F160W), will enable a better definition of the synchroton spectrum of the jet, constraining potential emission mechanisms.

GO 13786: Decoding Debris System Substructures: Imprints of Planets/Planetesimals and Signatures of Extrinsic Influences on Material in Ring-Like Disks

The HST-STIS discovery image of the debris disk around HD 202628, one of the stars targeted in this program (image by J.Krist)
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. Over the past decade, HST and Spitzer have provided complementary information on this topic, with Spitzer measuring thermal radiation from circumstellar dust and HST providing high-resolution mapping of debris disks in reflected light. Almost a dozen debris disk systems have currently been imaged; moreover, planetary companions to the young (60 Myr-old) F star, HR 8799, have also been imaged by both ground-based telescopes and HST. Many prior HST observations were made using the The coronagraph was associated with the High Resolution Camera on the Advanced Camera for Surveys. That instrument was not restored in SM4; however, coronagraphy is still possible using the occulting bar on the Space Telescope Imaging Spectrograph (STIS). The present program targets five systems with moderately inclined debris disks, including three G-dwarfs (HD 202628, HD 207129 and HD 202917) and two A-dwarfs (HD 14156, HR 4796). The goal is to obtain deep images that reveal the detailed structure of the disk, probing the likely development of planetary-mass objects.

GO 14062: The Fifth and Final Epoch

ESO image of the material surrounding the long-period Cepheid, RS Puppis
Cepheid variable stars have been the prime extragalactic distance indicator since Henrietta Leavitt's discovery of the period-luminosity relation described by Cepheids in the Small Magellanic Cloud. It was Hubble's identification of Cepheids in NGC 6822 that finally established that at least some nebulae were island universes. Cepheids and the extragalactic distance scale figure largely in HST's history, notably through the Hubble Constant Program, one of the initial Key Projects. HST has since observed Cepheids in more than 30 galaxies. Establishing a Galactic sample with reliable distance determinations is obviously crucial to this process. Long period Cepheids, with pulsation periods in excess of 25 days, play a key role, since they are more luminous, easier to detect and can be observed with higher photometric accuracy in distant galaxies. The present program builds on the Cycle 21 program GO 13334 (The Longest Period Cepheids, a bridge to the Hubble Constant) and aims to add to the sample of well-observed Galactic Cepheids by using spatial scanning on WFC3 to determine accurate parallaxes for nine Cepheids at distances up to 4 kpc from the Sun. Spatial scanning enables astrometry to an acuracy of ~40 microarcseconds, offering the prospect of distances accurate to 4% for individual Cepheids, and an overall distance scal calibration accurate to ~1%. Program GO 13334 acquired observations at 4 epochs for each star; the present program adds a fifth, solidifying the parallax determination by eliminating the potential for binary motion and resolving correlations between parallax and proper motion.

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