This week on HST


HST Programs: August 15 - August 21, 2016

Program Number Principal Investigator Program Title
13776 Michael D. Gregg, University of California - Davis Completing The Next Generation Spectral Library
14038 Jennifer Lotz, Space Telescope Science Institute HST Frontier Fields - Observations of Abell 370
14074 Roger Cohen, Universidad de Concepcion Opening the Window on Galaxy Assembly: Ages and Structural Parameters of Globular Clusters Towards the Galactic Bulge
14076 Boris T. Gaensicke, The University of Warwick An HST legacy ultraviolet spectroscopic survey of the 13pc white dwarf sample
14077 Boris T. Gaensicke, The University of Warwick The frequency and chemical composition of rocky planetary debris around young white dwarfs: Plugging the last gaps
14086 Jay Strader, Michigan State University Dynamical Confirmation of a Stellar-mass Black Hole in the Globular Cluster M62
14096 Dan Coe, Space Telescope Science Institute - ESA RELICS: Reionization Lensing Cluster Survey
14098 Harald Ebeling, University of Hawaii Beyond MACS: A Snapshot Survey of the Most Massive Clusters of Galaxies at z>0.5
14110 David Kent Sing, University of Exeter Charaterizing the atmosphere of the enlarged Neptune-mass planet HAT-P-26b
14119 Luciana C. Bianchi, The Johns Hopkins University Understanding Stellar Evolution of Intermediate-Mass Stars from a New Sample of SiriusB-Like Binaries
14122 Lise Christensen, University of Copenhagen, Niels Bohr Institute Unveiling stellar populations in absorption-selected galaxies
14127 Michele Fumagalli, Durham Univ. First Measurement of the Small Scale Structure of Circumgalactic Gas via Grism Spectra of Close Quasar Pairs
14163 Mickael Rigault, Humboldt Universitat zu Berlin Honing Type Ia Supernovae as Distance Indicators, Exploiting Environmental Bias for H0 and w.
14181 S Thomas Megeath, University of Toledo A Snapshot WFC3 IR Survey of Spitzer/Hershel-Identified Protostars in Nearby Molecular Clouds
14196 Gregory J. Herczeg, Peking University The Very Low Mass Object FW Tau b: An Edge-on Brown Dwarf Disk or a Planet Caught in Formation?
14204 Antonino Paolo Milone, Australian National University Multiple stellar populations in two young Large Magellanic Cloud clusters: NGC1755 and NGC1866
14209 Brian Siana, University of California - Riverside The Final UV Frontier: Legacy Near-UV Imaging of the Frontier Fields
14212 Karl Stapelfeldt, Jet Propulsion Laboratory A Snapshot Imaging Survey of Spitzer-selected Young Stellar Objects in Nearby Star Formation Regions*.t23
14216 Robert P. Kirshner, Harvard University RAISIN2: Tracers of cosmic expansion with SN IA in the IR
14219 John P. Blakeslee, Dominion Astrophysical Observatory Homogeneous Distances and Central Profiles for MASSIVE Survey Galaxies with Supermassive Black Holes
14220 Trent J. Dupuy, University of Texas at Austin Mapping the Substellar Mass-Luminosity Relation Down to the L/T Transition
14227 Casey Papovich, Texas A & M University The CANDELS Lyman-alpha Emission At Reionization (CLEAR) Experiment
14255 Sjoert van Velzen, The Johns Hopkins University A First Look at the Late Stages of Accretion in Tidal Disruption Flares
14259 Denija Crnojevic, Texas Tech University Resolved halo substructures beyond the Local Group: the assembly histories of NGC 253 and NGC 5128
14260 Drake Deming, University of Maryland A Metallicity and Cloud Survey of Exoplanetary Atmospheres Prior to JWST
14267 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
14327 Saul Perlmutter, University of California - Berkeley See Change: Testing time-varying dark energy with z>1 supernovae and their massive cluster hosts
14342 Howard E. Bond, The Pennsylvania State University HST Observations of Astrophysically Important Visual Binaries
14347 John Sebastian Pineda, University of Colorado at Boulder Joint VLA and HST Observations of Brown Dwarf Aurorae

Selected highlights

GO 14038: HST Frontier Fields - Observations of Abell 370


HST observations of the Frontier Fields cluster, Abell 370
The overwhelming majority of galaxies in the universe are found in clusters. As such, these systems offer an important means of tracing the development of large-scale structure through the history of the universe. Moreover, as intense concentrations of mass, galaxy clusters provide highly efficient gravitational lenses, capable of concentrating and magnifying light from background high redshift galaxies to allow detailed spectropic investigations of star formation in the early universe. Hubble imaging has already revealed lensed arcs and detailed sub-structure within a handful of rich clusters. At the same time, the lensing characteristics provide information on the mass distribution within the lensing cluster. The present program builds on the highly successful CLASH program,which used 17-colour ACS/WFC3 images to map 25 galaxy clusters, tracing the mas profile and the dark matter distribution. in addition, the observations identified several lensed galaxies at redshifts that enter the JWST domaine, with the most distant object lying at a redshift z~11, within a few hundred million years of the Big Bang. The Frontier Fields program is a large-scale Director's Discretionary program that capitalises on the latter characteristic by targeting 4-6 strong-lensing galaxy clusters for very deep optical and near-infrared imaging. WFC3 and ACS will be used to observe the clusters, with simultaneous imaging obtained in parallel of a nearby "blank" field. Since the observations need to made at a specific orientation, they are being taken in two sets, ~6 months apart, alternating between detectors. Abell 370 at z=0.375 is the sixth and final target. The present observations will provide the second epoch data, with WFC3-IR covering the cluster and ACS centred on the parallel field. These observations will close out the 3-year Frontier Fields program.

GO 14110: Characterizing the atmosphere of the enlarged Neptune-mass planet HAT-P-26b


Artist's impression an exo-Neptune
HAT-P-26b is a Neptune-mass planet orbiting a fairly anonymous 11th magnitude K dwarf, GSC 0320-01027, with a period of 4.23 days. The planet transits the parent star, and those transits were discovered in 2010 by the HATNet (Hungarian Automated Transit Netowrk) project - a network of small telescopes distributed in various sites around the globe, enabling near-continuous observations (weather permitting) of exoplanet transits. The planet has a mass only 6% that of Jupiter, comparable with that of Neptune. HAT-P-26b is almost twice as big as Neptune, however, with 56% the radius of Jupiter. This indicates that the planet has a low mean density, possibly due to the outer atmospheric layers being inflated due to its close proximity to the parent star. The present program aims to use the WFC3 G141 grism to measure the transmission spectrum of the planet during transit, searching for absorption features due to water, methane, sodium and potassium, as well as probing possible contributions from Rayleigh scattering that might illuminate the properties and composition of the outer atmosphere.

GO 14163: Honing Type Ia Supernovae as Distance Indicators, Exploiting Environmental Bias for H0 and w.


Supernova in M101
Supernovae have long attracted the attention of both amateur and professional astronomers as a means of studying the violent eruption and death of massive stars and degenerates. However, in the last decade they have also acquired considerable importance as distance indicators, tracing the expansion of the universe to redshifts well beyond the reach of more conventional yardsticks, such as cepheids, and providing a key underpinning for the hypothesised existence of dark energy. Understanding the supernovae themselves, and, in particular, their progenitors, is key to accurately interpreting their luminosities and distances. Recent observations have suggested that there may be a correlation between the brightnesses of Type Ia supernovae and some characteristics of their local environment; specifically, supernovae found in close proximity to star formation appear to be sub-luminous. The present SNAP program uses the UVIS camera on WFC3 to image the locations of supernovae that have been used to map the Hubble flow, and will use the UV-to-optical flux ratio to characterise the local environment, potentially offering a means of tightening the distribution in the Hubble diagram.

GO 14204: Multiple stellar populations in two young Large Magellanic Cloud clusters: NGC1755 and NGC1866


HST image of the LMC cluster, NGC 1866
Globular clusters are remnants of the first substantial burst of star formation in the Milky Way. With typical masses of a few x 105 solar masses, distributed among several x 106 stars, the standard picture holds that these are simple systems, where all the stars formed in a single starburst and, as a consequence, have the same age and metallicity. Until recently, the only known exception to this rule was the cluster Omega Centauri, which is significantly more massive than most clusters and has both double main sequence and a range of metallicities among the evolved stars. Over the past 5-10 years, Omega Cen has been joined by numerous other Galactic clusters, including NGC 2808, which shows evidence for three distinct branches to the main sequence, NGC 1851, 47 Tucanae and NGC 6752 - all relatively massive clusters. In almost all cases, the complexity of these systems has only emerged through the high precision observations possible with HST. Hubble is now being turned towards clusters in one of our nearest neighbours, the Large Magellanic Cloud. Previously, observations were obtained of the massive cluster, NGC 1846. The present program aims to extend coverage to two other clusters, NGC 1866 and NGC 1755. Both clusters are much younger than the halo Milky Way globulars, with ages of ~150 Myrs, but are similar in mass. The WFC3-UVIS camera will be used to obtain deep UV (F336W) and I-band (F814W) images to search for evidence of multiple populations.

Past weeks:
page by Neill Reid, updated 23/12/2014
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