This week on HST


HST Programs: March 6 - March 12, 2017

Program Number Principal Investigator Program Title
14096 Dan Coe, Space Telescope Science Institute - ESA RELICS: Reionization Lensing Cluster Survey
14109 Yue Shen, University of Illinois at Urbana - Champaign Host galaxy properties of z>~0.3 broad-line AGN with direct black hole masses from reverberation mapping
14120 Jarle Brinchmann, Universiteit Leiden He II emission as a tracer of ultra-low metallicity and massive star evolution
14127 Michele Fumagalli, Durham Univ. First Measurement of the Small Scale Structure of Circumgalactic Gas via Grism Spectra of Close Quasar Pairs
14141 Guy Worthey, Washington State University NGSL Extension 1. Hot Stars and Evolved Stars
14178 Matthew A. Malkan, University of California - Los Angeles WFC3 Infrared Spectroscopic Parallel Survey: The WISP Deep Fields
14181 S Thomas Megeath, University of Toledo A Snapshot WFC3 IR Survey of Spitzer/Hershel-Identified Protostars in Nearby Molecular Clouds
14235 Sangmo Tony Sohn, Space Telescope Science Institute Globular Cluster Orbits from HST Proper Motions: Constraining the Formation and Mass of the Milky Way Halo
14240 Bart P. Wakker, University of Wisconsin - Madison Mapping the circumgalactic medium of two large spiral galaxies
14248 Michael J Koss, Eureka Scientific Inc. Studying Dual AGN Activity in the Final Merger Stage
14251 Amy E. Reines, National Optical Astronomy Observatory, AURA The Structures of Dwarf Galaxies Hosting Massive Black Holes
14456 Mark Brodwin, University of Missouri - Kansas City Determining the Role of Merging in the Growth of the Galaxy Cluster Population in the Massive and Distant Clusters of WISE Survey
14597 Jay Farihi, University College London An Ultraviolet Spectral Legacy of Polluted White Dwarfs
14606 Brooke Devlin Simmons, University of California - San Diego Secular Black Hole Growth and Feedback in Merger-Free Galaxies
14614 Jon Mauerhan, University of California - Berkeley Death or Survival? Determining the nature of SNe IIn-P explosions
14618 Michael Shara, American Museum of Natural History Ultraviolet Flashers in M87: Rapidly Recurring Novae as SNIa Progenitors
14628 Danielle Berg, University of Wisconsin - Milwaukee The Evolution of C/O in Low Metallicity Dwarf Galaxies
14633 Kevin France, University of Colorado at Boulder A SNAP UV Spectroscopic Study of Star-Planet Interactions
14644 Pieter van Dokkum, Yale University Exploring the extremely low surface brightness sky: distances to 23 newly discovered objects in Dragonfly fields
14653 James Lowenthal, Smith College The most luminous galaxies: strongly lensed SMGs at 1
14684 David V. Bowen, Princeton University What is a Galaxy Halo Really Like?
14704 Charlie Conroy, Harvard University A Year in the Whirlpool
14717 Iair Arcavi, University of California - Santa Barbara What is Enhancing the Tidal Disruption Rate of Stars in Post-Starburst Galaxies?
14729 Rajib Ganguly, University of Michigan A New Twist in the Quasar Radio Dichotomy: The Case of the Missing Outflows
14730 Andrew Goulding, Princeton University High spatial resolution imaging of AGN-driven super-bubbles in two low-redshift quasars
14734 Nitya Kallivayalil, The University of Virginia Milky Way Cosmology: Laying the Foundation for Full 6-D Dynamical Mapping of the Nearby Universe
14754 Crystal Linn Martin, University of California - Santa Barbara Confronting the 3D Orientation of Galactic Disks in Space: Disk Structure vs. Circumgalactic Gas Flows
14767 David Kent Sing, University of Exeter The Panchromatic Comparative Exoplanetary Treasury Program
14779 Melissa Lynn Graham, University of Washington A NUV Imaging Survey for Circumstellar Material in Type Ia Supernovae
14798 Michal Drahus, Uniwersytet Jagiellonski Origin and Evolution of the First Known Ultra-Young Asteroid Family and its Doubly-Synchronous Binary Member
14811 Laurent Lamy, Observatoire de Paris - Section de Meudon The Grand Finale : probing the origin of Saturn s aurorae with HST observations simultaneous to Cassini polar measurements
14840 Andrea Bellini, Space Telescope Science Institute Schedule Gap Pilot
14845 Martha L. Boyer, Space Telescope Science Institute A Search for Stellar Dust Production in Leo P, a Nearby Analog of High Redshift Galaxies
14891 William B. Sparks, Space Telescope Science Institute Confirming the ice plumes of Europa
14896 Matthew Bayliss, Massachusetts Institute of Technology Precise Photometric Redshifts For Two Bright z>8 Galaxies

Selected highlights

GO 14235: Globular Cluster Orbits from HST Proper Motions: Constraining the Formation and Mass of the Milky Way Halo


Hubble image of the metal-poor globular cluster, M15
Globular clusters are members of the Galactic halo population, representing remnants from the first extensive period of star formation in the Milky Way. As such, the properties of the 106 to 107 stellar constituents can provide crucial insight into the earliest stages of galaxy formation. Until recently, conventional wisdom was that these are simple systems, where all the stars formed in a single starburst and, as a consequence, have the same age and metallicity. One of the most surprising disoveries in recent years is the realisation that this simple picture no longer holds. A substantial number of thee systems show complex structure in the colour-magnitude diagram, indicating the presence ofmultiple stellar populations. Current globulars may therefore represent the remnant cores of dwarf galaxy-like systems. Regardless of their origin, the present systems can also serve to map the potential of the Milky Way. Undertaking that analysis demands the determination of three-dimensional motions, requiring that we obtain accurate absolute proper motions for these systems. That is now becoming possible; thanks to Hubble's longevity, a significant number of clusters have imaging data from 10-20 years ago. Coupled with new observations, those data provide the baseline to allow measurement of the tranverse motion, and hence orbit determinations.

GO 14181: A Snapshot WFC3 IR Survey of Spitzer/Hershel-Identified Protostars in Nearby Molecular Clouds


An image of the Orion Nebula superimposed on the 13CO map of Orion A (from this link ).
Giant molecular cloud complexes serve as nurseries for star formation. Deeply embedded in dust and gas, young stars are generally extremely difficult to detect at optical wavelengths. Consequently, these complexes have been subject to extensive scrutiny at near- and mid-infrared wavelengths, initially through ground-based observing campaigns and more recently by the Spitzer and Herschel space missions. Those observations have resulted in the identification of numerous embedded sources, young stellar objects (YSOs) that are still accreting from the surrounding molecular gas .he present proposal aims to follow up on those discoveries by obtaining WFC3-IR SNAPs of candidate protostars in several molecular cloud complexes. These observations will provide an excellent complement to Spitzer and Herschel since, while HST cannot offer either the same areal coverage or sensitivity at mid-infrared wavelegths, the imaging has a resolution close to 0.1 arcsecond, an order of magnitude higher than the Spitzer images. The observations are therefore capable of detecting very faint companions, with luminosities consistent with sub-stellar masses, as well as identifying jets and outflows associated with the star formation process. The present program is using the F160W filter to obtain H-band images and determine the true nature of these objects.

GO 14767: The Panchromatic Comparative Exoplanetary Treasury Program


Artist's impression of the GJ 1214 system
The first exoplanet, 51 Peg b, was discovered through radial velocity measurements in 1995. 51 Pegb was followed by a trickle, and then a flood of other discoveries, as astronomers realised that there were other solar systems radically different from our own, where "hot jupiters" led to short-period, high-amplitude velocity variations. Then, in 1999, came the inevitable discovery that one of those hot jupiters. HD 209458b, was in an orbit aligned with our line of sight to the star, resulting in transits. Since that date, the number of known transiting exoplanet systems has grown to more than 100 from ground-based observations, most detected through wide-field photometric surveys, while the high-sensitivity data provided by Kepler has added a further 1000+ confirmed systems and ~2000 additional candidates. Transiting systems not only provide an accurate measure of the planetary radius (at least relative to the parent star), they also provide us with an opportunity to probe the atmospheric composition through spectroscopy during the transit. Hubble has made significant inroads in this area, while Spitzer has contributed measurements of planetary emissivity through observations during and after eclipse. The James Webb Space Telescope has the capability to revolutionise our knowledge in this field through highly sensitiive observations at near and mid-infra red wavelengths. The present program aims to lay the foundation for those programs by using Hubble to compile multiwavelength (UV to near-IR) spectroscopic observations of 20 exoplanets. The targets are all gas giants, ranging from super-jovian masses to neptunian masses. The observations will be obtained with the Space Telescope Imaging Spectrograph and the near-infrared grisms on Wide Field Camera 3.

GO 14891: Confirming ice plumes of Europa


The HST imaging of a potential water plume around Europa's south pole superimposed on an image of the satellite
Europa is the smallest, and the most intriguing, of the four Galilean satellites of Jupiter. With a diameter of 3139 km, Europa is almost twice the size of Earth's moon and significantly larger than Mercury. In 1957, Gerard Kuiper commented that both infrared spectroscopy and the optical colours and albedo suggested that Jovian satellite II (Europa) is covered "by H2O snow". Images taken by the Voyager space probes in the late 1970s (see left) reveal a smooth surface, with only a handful of craters larger than a few kilometres. These features are consistent with a relatively young, icy surface. Subsequent detailed investigations by the Galileo satellite strongly suggest that a substantial body of liquid water, heated by tidal friction, underlies a 5 to 50 km thick icy crust. The presence of this subterranean (subglacial?) ocean clearly makes Europa one of the two most interesting astrobiology targets in the Solar System. Most recently, analysis of observations taken by the Space Telescope imaging Spectrograph (STIS) on Hubble indicated the presence of an extended cloud of Lyman-alpha emission near the polar regions while Europa was furthest in its orbit from Jupiter, strongly suggesting that Europa's oceans may be vaporising into space.Follow-up observations on two further occasions earlier in 2014 failed to detect any emission, suggesting that the emission is either sporadic or periodic; in the latter case, the emission might be related to the location of Europa within its orbit and the consequent tidal strain imposed by Jupiter. Over the past year, Hubble has monitored Europa' activity through several programs. The present program is using UV imaging with the Space Telescope Imaging Spectrograph to search for absorption features as Europa transits across Jupiter.

Past weeks:
page by Neill Reid, updated 2 /1/2017
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