This week on HST


HST Programs: October 13 - October 19, 2014

Program Number Principal Investigator Program Title
13281 Sebastiano Cantalupo, University of California - Santa Cruz Illuminating the Dark Phases of Galaxy-Formation with the Help of a z=2.4 Quasar
13282 You-Hua Chu, University of Illinois at Urbana - Champaign A Search for Surviving Companions of Type Ia Supernovae in the Large Magellanic Cloud
13308 Ming Zhao, The Pennsylvania State University Near-IR spectroscopy of the highly inflated, hottest known Jupiter KOI-13.01
13339 Matthias Stute, Eberhard Karls Universitat, Tubingen R Aqr: a prototype for non-relativistic astrophysical jets and a key for understanding jet formation
13361 William P. Blair, The Johns Hopkins University Discovering and Characterizing the Young Supernova Remnant Population in M101
13388 Gregory James Schwarz, American Astronomical Society Fundamental properties of novae outburst: Coordinated HST and XMM ToO observations
13434 Tiffany Meshkat, Universiteit Leiden Transmission spectroscopy through the debris disk of Fomalhaut
13435 Matteo Monelli, Instituto de Astrofisica de Canarias Multiple populations in external globular glusters: the Fornax dSph, the LMC, and the SMC
13447 Selma E. de Mink, Carnegie Institution of Washington The massive monsters living deep in the Tarantula nebula: How massive are they really?
13466 Kailash C. Sahu, Space Telescope Science Institute Determining the Mass of Proxima Centauri through Astrometric Microlensing
13467 Jacob L. Bean, University of Chicago Follow The Water: The Ultimate WFC3 Exoplanet Atmosphere Survey
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
13482 Britt Lundgren, University of Wisconsin - Madison The Evolving Gas Content of Galaxy Halos: A Complete Census of MgII Absorption Line Host Galaxies at 0.7 < z < 2.5
13483 Goeran Oestlin, Stockholm University eLARS - extending the Lyman Alpha Reference Sample
13633 John R. Spencer, Southwest Research Institute A Kuiper Belt Object for the New Horizons Mission
13643 Gaspard Duchene, University of California - Berkeley Imaging the tenuous dusty atmosphere of edge-on protoplanetary disks
13661 Matthew Auger, University of Cambridge A SHARP View of the Structure and Evolution of Normal and Compact Early-type Galaxies
13663 Susan D. Benecchi, Planetary Science Institute Precise Orbit Determination for a New Horizons KBO
13671 Harald Ebeling, University of Hawaii Beyond MACS: A Snapshot Survey of the Most Massive Clusters of Galaxies at z>0.5
13712 Kunio M. Sayanagi, Hampton University Target of Opportunity Observation of an Episodic Storm on Uranus
13729 Andy Lawrence, University of Edinburgh, Institute for Astronomy Slow-blue PanSTARRS transients : high amplification microlens events?
13730 Adam Leroy, The Ohio State University Maps of Recent Star Formation to Match ALMA Observations of the Nearest Nuclear Starburst
13731 Eileen T Meyer, Space Telescope Science Institute The Real Impact of Extragalactic Jets on Their Environments: Measuring the Advance Speed of Hotspots with HST
13740 Daniel Stern, Jet Propulsion Laboratory Clusters Around Radio-Loud AGN: Spectroscopy of Infrared-Selected Galaxy Clusters at z>1.4
13773 Rupali Chandar, University of Toledo H-alpha LEGUS: Unveiling the Interplay Between Stars, Star Clusters, and Ionized Gas
13779 Sangeeta Malhotra, Arizona State University The Faint Infrared Grism Survey (FIGS)
13819 Trent J. Dupuy, University of Texas at Austin Dynamical Masses for Free-Floating Planetary-Mass Binaries
13834 Roeland P. van der Marel, Space Telescope Science Institute The Proper Motion Field along the Magellanic Bridge: a New Probe of the LMC-SMC interaction
13842 Frederick Hamann, University of Florida Testing the Youth and Transition Object Status of FeLoBAL Quasars
13845 Adam Muzzin, Sterrewacht Leiden Resolved H-alpha Maps of Star-forming Galaxies in Distant Clusters: Towards a Physical Model of Satellite Galaxy Quenching
13858 Annalisa De Cia, Weizmann Institute of Science The environment of the rarest and most energetic supernovae: do pair-instability explosions exist in the nearby Universe?
13864 David Jewitt, University of California - Los Angeles Hubble Imaging of a Newly Discovered Active Asteroid

Selected highlights

GO 13282: A Search for Surviving Companions of Type Ia Supernovae in the Large Magellanic Cloud


Combined HST and Chnadra imaging of the supernova remnant SNR 0509-67.5 in the LMC
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. In double degenerate systems, the white dwarfs merge and explode; in the single degenerate mode, the non-degenerate companion is likely to survive, albeit in a stripped, ablated form. 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 obtain a better udnerstanding of the underlying mechanism and the distribution of intrinsic properties of these exploding stars.Relatively nearby supernovae that can be probed in detail are therefore crucial to the large mapping of the cosmic flow. The present program aims to probe whether the double degenerate or single degenerate mode of formation is more important by using HST imaging to search for survivors in a sample of nine supernova remnants in the LMC. If the double degenerate mechanism is the dominant mechanism, then few survivors of the progenitor explosion will be found.

GO 13435: Multiple populations in external globular glusters: the Fornax dSph, the LMC, and the SMC


The colour-magnitude diagram from the LMC cluster, NGC 1846
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. Adecade ago, 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. Since then detailed photometric investigations, based primarily on data taken by HST's Advanced Camera for Surveys and Wide-Field Camera 3, have shown that many other clusters have multiple populations. Examples include NGC 2808, which shows evidence for three distinct branches to the main sequence, NGC 1851, 47 Tucanae and NGC 6752 - all relatively massive clusters. However, even classical extremely metal-poor systems, such as NGC 6397, show some evidence for a broadening of the main sequence that probably reflects abundance differences (metals or helium) among the stellar members. Globular clusters are also present in other galaxies, and past HST programs have probed a number of clusters in the nearby Large Magellanic Cloud. The present program aims extend coverage to additional clusters in the LMC, together with systems in the Small Magellanic Cloud and the Fornax dwarf spheroidal. These clusters will be targeted for observation with WFC3, both UVIS and near-IR channels, and with ACS.

GO 13633: A Kuiper Belt Object for the New Horizons Mission


Hubble Space Telescope images of the Pluto system, including the recently discovered moons, P4 and P5
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. The Pluto encounter represents the first phase of the originally-proposed mission. Following the fly-by, set for Bastille day in 2015, the aim is to re-direct New Horizons towards one or more smaller members of the Kuiper Belt, with the goal of providing a closer look at these icy bodies. However, New Horizons needs to identify an appropriate target - a KBO with orbital parameters such that New Horizons can use its modest complement of remaining fuel to reach the target. Adding a further complication, Pluto happens to lie within 5 degrees of the Galactic Plane and the consequent high star density has proven a barrier to deep ground-based searches. As a consequence, the New Horizons team was awarded Hubble time to search an area roughly the size of the full moon for a suitable target. These observations are significantly deeper than previous surveys, and as a result will lead to a better understanding of the size distribution of smaller objects (< 20 km diameter) in the Kuiper Belt.

GO 13834: The Proper Motion Field along the Magellanic Bridge: a New Probe of the LMC-SMC interaction


The Large Magellanic Cloud (upper left) with the Small Magellanic Cloud (right) and the (foreground) Galactic globular cluster47 Tucanae
The Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC) are the most massive satellites of the Milky Way galaxy. The orbital motions of these systems can be used to probe the mass distribution of Milky Way, and backtracking the orbits can shed light on how the three systems have interacted, In particular, the well known Magellanic Stream, stretching between the two Clouds, is thought to be a product either of interactions between the Clouds, or of ram-stripping of gas from the LMC on its last passage through the Plane of the Milky Way. Understanding the full scope of the interactions demands knowledge of the tangential motions of these systems - that is, proper motion measurements. Given the distances of the Clouds (~50 kpc.), the actual motions amount to only a few milliarcseconds, but the high spatial resolution and high stability of HST imaging makes such measurements possible. Past observing programs (eg GO 11730) have concentrated on the LMC, using the now-defunct ACS High Resolution Camera (ACS/HRC), the Planetary Camera on WFPC2 and the UVIS camera on WFC3 to target known QSOs lying behind the Clouds; the QSOs serve as fixed reference points for absolute astrometry of the numerous foreground LMC/SMC stars. A recent Cycle 21 program focused on the SMC, targeting 30 newly identified background QSos for WFC3 observations over a two-year period. The present program exapnds observations to several fields along the Magellanic bridge, a complex of gas and stars that conencts the two clouds, and will test the hypothsesis that the clouds are undergoing their first interaction with teh Milky Way.

Past weeks:
page by Neill Reid, updated 5/9/2014
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