This week on HST


HST Programs: June 27 - July 3, 2016

Program Number Principal Investigator Program Title
13760 Derck L. Massa, Space Science Institute Filling the gap --near UV, optical and near IR extinction
14080 Anne Jaskot, Smith College LyC, Ly-alpha, and Low Ions in Green Peas: Diagnostics of Optical Depth, Geometry, and Outflows
14092 Susan D. Benecchi, Planetary Science Institute Collisional Processing in the Kuiper Belt and Long-Range KBO Observations by New Horizons
14105 Jonathan David Nichols, University of Leicester Observing Jupiter's FUV auroras near Juno orbit insertion
14118 Luigi R. Bedin, Osservatorio Astronomico di Padova The end of the White Dwarf Cooling Sequences of Omega Centauri
14123 James Colbert, Jet Propulsion Laboratory Does All The Lyman Continuum Emission Escape From Young, Low Mass Starbursts?
14127 Michele Fumagalli, Durham Univ. First Measurement of the Small Scale Structure of Circumgalactic Gas via Grism Spectra of Close Quasar Pairs
14133 David Polishook, Weizmann Institute of Science Establishing an evolutionary sequence for disintegrated minor planets
14146 Stephen S. Lawrence, Hofstra University Light Echoes and Environment of SN 2014J in M82
14152 pierre guillard, CNRS, Institut d'Astrophysique de Paris Hot gas cooling and turbulence in the 3C326N radio-galaxy
14163 Mickael Rigault, Humboldt Universitat zu Berlin Honing Type Ia Supernovae as Distance Indicators, Exploiting Environmental Bias for H0 and w.
14171 Guangtun Zhu, The Johns Hopkins University Characterizing the Circumgalactic Medium of Luminous Red Galaxies
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
14199 Patrick Kelly, University of California - Berkeley Refsdal Redux: Precise Measurements of the Reappearance of the First Supernova with Multiple Resolved Images
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
14228 John Charles Raymond, Smithsonian Institution Astrophysical Observatory Thermal Equilibration and Cosmic-Ray Acceleration in Astrophysical Shocks: UV Spectra of the SN1006 Remnant
14239 Christy A. Tremonti, University of Wisconsin - Madison Direct Imaging of Galactic Winds in Extreme Starburst Galaxies
14251 Amy E. Reines, National Optical Astronomy Observatory, AURA The Structures of Dwarf Galaxies Hosting Massive Black Holes
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
14277 John Thomas Stocke, University of Colorado at Boulder Probing Hot Gas in Spiral-Rich Galaxy Groups
14327 Saul Perlmutter, University of California - Berkeley See Change: Testing time-varying dark energy with z>1 supernovae and their massive cluster hosts
14357 Eleonora TROJA, University of Maryland Identify the signature of neutron star mergers through rapid Chandra/Hubble observations of a short GRB
14516 Robert M. Quimby, San Diego State University UV Spectroscopy of the Superluminous Supernova Gaia16apd
14524 Javier Licandro, Instituto de Astrofisica de Canarias WFC3 imaging of active asteroid P/2016 G1

Selected highlights

GO 14092: Collisional Processing in the Kuiper Belt and Long-Range KBO Observations by New Horizons


New Horizons image of the Pluto; the images of other Kuiper belt objects will have much lower resolution
The Kuiper Belt lies beyond the orbit of Neptune, extending from ~30 AU to ~50 AU from the Sun, and includes at least 70,000 objects with diameters exceeding 100 km. Setting aside Pluto, the first trans-Neptunian objects were discovered in the early 1990s. Most are relatively modest in size, with diameters of a few hundred km and photometric properties that suggest an icy composition, similar to Pluto and its main satellite, Charon. In recent years, a handful of substantially larger bodies have been discovered, with diameters of more than 1000 km; indeed, one object, Eris (2003 UB13), is slightly larger than Pluto (2320 km) and 25% more massive. We know the mass for Eris because it has a much lower mass companion, Dysnomia, which orbits Eris with a period of 16 days (see this recent press release ). Pluto itself has at least 5 companions: Charon, which is about 1/7th the mass of Pluto, and the much smaller bodies, Hydra, Nix, P4 and P5 discovered through HST observations within the last few years. The New Horizons Mission was launched on January 19th 2006 with the prime purpose of providing the first detailed examination of Pluto. Following the Pluto fly-by on Bastille day 2015, the program aims to redirect the probe towards one or more smaller members of the Kuiper Belt, with the goal of providing a closer look at these icy bodies. Based on Hubble imaging, a suitable prime target has been identified: 2014 MU69, a ~30 km KBO lying ~44 AU from the Sun. In addition, New Horizons is expected to take longer-range, monochromatic images of up to 10 other KBOs. The present program targets eight of those objects with Hubble, using the Wide-Field camera 3 UVIS channel to obtain multicolour data to characterise the surface properties, and to search for possible binary companions.

GO 14118: The end of the White Dwarf Cooling Sequences of Omega Centauri


ACS imaging of the central regions of Omega Cen
Globular clusters are members of the Galactic halo population, which formed during 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. Hubble has conducted a significant number of observing programs targeting these systems, with the majority designed to obtain moderately deep, multicolour imaging data of a range of clusters. Those programs probe evolved stars, on the red giant and horizontal branch, and generally extend only a few magnitudes below the main-sequence turnoff. Noetheless, the exqusite photometric precision offered by HST's camera has revealed that the majority of these systems have multiple stellar populations, rather than conforming to traditional single-burst formation models. A few clusters have been studied in detail - specifically, the two nearest clusters, NGC 6397, an extremely metal-poor cluster, and M4, a moderately metal-rich systems; Omega Centauri, one of the most massive clusters, perhaps even the remnant core of a dwarf galaxy; and 47 Tucanae, one of the higher metallicity systems, lying in the foreground of the Small Magellanic Cloud. Deep imaging of all four clusters has succeeded in clear detecion of the white dwarf cooling sequence in those clusters, and those data have been used to derive age estimates. The present program builds on past observations in aiming to probe the multiple white dwarf cooling sequences in Omega Cen. The WFC3/UVIS and ACS/WFC cameras will be used to obtain multi-colour imaging of the cluster. Those observations should enable measurement over the full extent of the white dwarf cooling sequences, offering the potential of resolving the nature and origin(s) of the distinct stellar populations.

GO 14146: Light Echoes and Environment of SN 2014J in M82


Image of the recent supernova in M82, Jan 24th (Katzman Automated Imaging Telescope/LOSS)
Type Ia supernovae are generally believed to be produced by the explosive deflagration of white dwarf star that exceeds the Chandrasekhar due to accretion from a binary companion, either a hydrogen-burning main-sequence/red giant star or another degenerate. Besides providing crucial information on stellar evolution and how stars enrich the interstellar medium, Type Ia supernovae have acquired global importance in recent years through their use as distance indicators. Indeed, these objects played a crucial role in identifying dark energy and the accelerating universe. In that context, it is important to understand the distribution of intrinsic properties of these exploding stars, and whether those properties, particularly luminosity, correlate with other parameters, such as metallicity. Relatively nearby supernovae that can be probed in detail are therefore crucial to the large mapping of the cosmic flow. Astronomers were therefore delighted with the discovery of a type Ia supernova in the relatively nearby starburst galaxy, M82 (d~3.5 Mpc). This object, designated SN2014J, was discovered on January 21st by a group of UCL undergraduates and their lecturer in a series of short exposures taken as a quick test as clouds closed in on London's Mill Hill Observatory. The supernova reached maximum at V~10.5 in early February and has since declined ino obscurity. The current program is part of a series of HST imaging programs that aim to probe the immediate environments of the supernova by searching for evidence of light echoes - reflections of the original explosion produced by interstellar features in the vicinity of the supernova.

GO 14327: 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.

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