This week on HST


HST Programs: October 14 - October 20, 2013

Program Number Principal Investigator Program Title
12861 Xiaohui Fan, University of Arizona Morphologies of the Most UV luminous Lyman Break Galaxies at z~3
12880 Adam Riess, The Johns Hopkins University The Hubble Constant: Completing HST's Legacy with WFC3
12892 Yue Shen, Carnegie Institution of Washington Imaging the Host Galaxies of Low-Redshift Quasars with Associated Absorbers
12930 Carrie Bridge, California Institute of Technology WISE Discovered Ly-alpha Blobs at High-z: The missing link?
12943 Yujin Yang, Max-Planck-Institut fur Astronomie, Heidelberg Testing the Cold Stream Accretion Model Using Lyman Alpha Blobs
12966 Roeland P. van der Marel, Space Telescope Science Institute The Nature of Dark Matter: Halo Cusps or Cores from dSph internal proper motion dynamics
12982 Nicolas Lehner, University of Notre Dame Are the Milky Way's High Velocity Clouds Fuel for Star Formation or for the Galactic Corona?
12990 Adam Muzzin, Sterrewacht Leiden Size Growth at the Top: WFC3 Imaging of Ultra-Massive Galaxies at 1.5 < z < 3
13002 Rik Williams, Carnegie Institution of Washington Monsters at the Dawn of the Thermal Era: Probing the extremes of galactic mass at z>2.5
13046 Robert P. Kirshner, Harvard University RAISIN: Tracers of cosmic expansion with SN IA in the IR
13057 Kailash C. Sahu, Space Telescope Science Institute Detecting and Measuring the Masses of Isolated Black Holes and Neutron Stars through Astrometric Microlensing
13113 C. S. Kochanek, The Ohio State University ENERGY DEPENDENT X-RAY MICROLENSING AND THE STRUCTURE OF QUASARS
13297 Giampaolo Piotto, Universita degli Studi di Padova The HST Legacy Survey of Galactic Globular Clusters: Shedding UV Light on Their Populations and Formation
13312 Danielle Berg, University of Minnesota - Twin Cities The Evolution of C/O in Low Metallicity Dwarf Galaxies
13329 Jonathan D. Nichols, University of Leicester Discovering the nature of the star-planet interaction at WASP-12b
13332 Seth Redfield, Wesleyan University A SNAP Survey of the Local Interstellar Medium: New NUV Observations of Stars with Archived FUV Observations
13335 Adam Riess, The Johns Hopkins University HST and Gaia, Light and Distance
13346 Thomas R. Ayres, University of Colorado at Boulder Advanced Spectral Library II: Hot Stars
13355 Bruce McCollum, Catholic University of America Uncovering the Nature of the Evolving Remnant Star of a Recent Stellar Merger
13364 Daniela Calzetti, University of Massachusetts - Amherst LEGUS: Legacy ExtraGalactic UV Survey
13375 Dougal Mackey, Australian National University Deep photometry of two accreted families of globular clusters in the remote M31 halo
13397 Luciana C. Bianchi, The Johns Hopkins University Understanding post-AGB Evolution: Snapshot UV spectroscopy of Hot White Dwarfs
13410 Cristina Pallanca, Universita di Bologna COSMIC-LAB: a BSS orbiting a NS? The companion to the supermassive NS in NGC6440.
13418 Daniel Apai, University of Arizona Patchy Clouds and Rotation Periods in Directly Imaged Exoplanets
13442 R. Brent Tully, University of Hawaii The Geometry and Kinematics of the Local Volume
13448 Andrew J. Fox, Space Telescope Science Institute - ESA The Closest Galactic Wind: UV Properties of the Milky Way's Nuclear Outflow
13451 Frederick Hamann, University of Florida A Study of PG Quasar-Driven Outflows with COS
13462 Brian E. Wood, Naval Research Laboratory Tracking the Winds of Red Giants from the Star to the ISM
13472 Wendy L. Freedman, Carnegie Institution of Washington The Hubble Constant to 1%? STAGE 4: Calibrating the RR Lyrae PL relation at H-Band using HST and Gaia Parallax Stars
13477 C. S. Kochanek, The Ohio State University Unmasking the Supernova Impostors
13480 Andrew J. Levan, The University of Warwick Super-luminous supernovae without host galaxies
13490 Jason A. Surace, California Institute of Technology Resolving the Reddest Extragalactic Sources Discovered by Spitzer: Strange Dust-Enshrouded Objects at z~2-3?
13498 Jennifer Lotz, Space Telescope Science Institute HST Frontier Fields - Observations of MACSJ0717.5+3745
13609 David Jewitt, University of California - Los Angeles Investigating the Trigger Mechanism for Newly Discovered Main Belt Comet P/2013 P5
13611 Nial R. Tanvir, University of Leicester The nature of the low redshift ultra-long GRB130925A: core collapse or tidal disruption?

Selected highlights

GO 12930: WISE Discovered Ly-alpha Blobs at High-z: The missing link?


Lab-1, the largest Lyman-alpha blob currently known, at z=3.1
Lyman-alpha blobs are large concentrations of gas that have been detected through their strong emission of Lyman alpha radiation. Most of those found have been foudnt rhough imaging at optical wavelengths, and therefore tend to lie at reshifts exceeding z=2. Some of these form coherent structures, including 3-D ~70-Mpc-scale filamentary structures. The present program aims to capitalise on recent discoveries made by the Wide-field infrare Survey Explorer. WISE has identified a number of Ly-alpha emitting blobs that have strikingly different energy distributions at near- and mid-infrared wavelengths, strongly suggestive of the presence of substantial quantities of dust. These objects have radically different energy distributions that the optically-identified LABs at z>2. The present program builds on a Cycle 19 program (GO 12481) and will use H-band observations with the WFC3-IR camera to obtain high-resolution images of these unusual systems in ther est-frame optical wavelengths, mapping both the overall energy distribution and the detailed morphology in Lyman-alpha and the rest-frame UV continuum.

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 of those 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 vby 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 F81wW (V and IK) where necessary.

GO 13418: Patchy Clouds and Rotation Periods in Directly Imaged Exoplanets


Ground-based imaging the the very low-mass brown dwarf binary, 2MASS1207
Recent years have seen the discovery of numerous extrasolar planets. Initially, the primary source was from radial velocity monitoring, although more recently the superb photometric properties of the Kepler mission have led to the discovery of numerous transiting systems. Lagging behind in numbers, but offering the greatest prospect for probing physical conditions, is direct imaging. A handful of systems withr esolved planetary companions have been discovered, most notably the multi-planet system around the nearby A-type star,HR 8799. The present program targets two objects - 2MASS1207B, the planetary-mass wide companion to the brown dwarf, 2MASS1207A, a member of the TW Hydrae association; and AB Pictoris B, the companion to a K-type member of the Tucana-Horologium group. Both of these systems are likely to have ages around 10-20 million years, leading to mass estimates of 7-14 jupiter masses for the companions and temperatuers in the 700 to 1,000K range. Both binary systems have wide separations, suggesting that' the companions may be more likely to be very low-mass brown dwarfs rather than planetary objects that formed wthin a circumstellar disk, but the situation remains somewhat ambiguous. In any case, these very low-mass objects provide an opportunity to probe the atmospheric characteristics at such low temperatures. Observations of isolated brown dwarfs have shown evidence for systematic variations in brightness, possibly due to dust within the atmosphere forming clouds, perhaps giving the dwarf's surface a banded appearance, similar to Jupiter. The clouds themselves may appear and disappear over relatively short timescales, leading to photometric variations at particular wavelengths. Past programs have used both Spitzer and HST to monitor spectral variability in a number of systems. The present program aimes to expand observations to these two planetary-mass wide companions.

GO 13609: Investigating the Trigger Mechanism for Newly Discovered Main Belt Comet P/2013 P5


Asteroid 596-Scheila, the prototype main-belt coment, imaged by Peter Lake in December, 2010
The term 'comet" is generally associated with low-mass, volatile-rich solar system objects that spend most of their life at very lage distances from the Sun, plunging only rarely into the inner regions where they acquire extended tails due to outgassing. Sometimes those obejcts are captured into short-period, eccentric orbits, leading to rapid depletion of the volatile content in rapidly-successive perihelion passages. However, recent years have seen growing evidence of another class of cometes exist: comets with near-circular orbits that place them between Mars and Jupiter, within the realm of the Main Belt of asteroids. One of the first candidate main belt comets, as these objects have been dubbed, is the asteroid Scheila. Discovered by the Heidelberg astronomer August Kopff in 1906, and named after an English student with whom he was acquainted, this is one of the larger known asteroids, with a diameter estimated as ~110 km. Early December 2010, Steve Larson (of Arizona's Lunar and Planetary Laboratory) noted that Scheila had sprouted a coma halo in observations taken by the Catalina Sky Survey. An examination of archival images revealed no evidence for activity throughout October and November, but a possible onset on December 3rd. The asteroid 1979 OW7/1996 N2 exhibited similar behaviour in 1996 and again in 2002; the initial outburst was ascribed to a collision, but the second event suggests that the activity is intrinsic rather than externally stimulated. More recently, the Pan-STARRS survey has contributed two objects: the asteroid 2006 VW139, imaged during an outburst; and Main Belt Comet 2013-P5. The present HST target-of-opportunity program has been triggered in response to the latter discovery, using high-resolution visual imaging with Wide-Feld Camera 3 to probe the detailed nature of the outburst. The first set of observations were taken on September, revealing significant changes in morphology within a two-week period. The present program builds on those reslts by mapping out a series of ~monthly observations to track the subsequent decline in activity with the aim of better understanding the mechanism that triggered the outburst.

Past weeks:
page by Neill Reid, updated 14/10/2012
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