This week on HST


HST Programs: July 6 - July 12, 2015

Program Number Principal Investigator Program Title
13647 Ryan Foley, University of Illinois at Urbana - Champaign Testing the Standardizability of Type Ia Supernovae with the Cepheid Distance of a Twin Supernova
13650 Kevin France, University of Colorado at Boulder The MUSCLES Treasury Survey: Measurements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanetary Systems
13656 Matthew Hayes, Stockholm University Unveiling the Dark Baryons: The First Imaging of Circumgalactic OVI in Emission
13667 Marc W. Buie, Southwest Research Institute Observations of the Pluto System During the New Horizons Encounter Epoch
13671 Harald Ebeling, University of Hawaii Beyond MACS: A Snapshot Survey of the Most Massive Clusters of Galaxies at z>0.5
13676 Eileen T Meyer, University of Maryland Baltimore County Solving the X-ray Origin Problem in Kiloparsec-Scale Relativistic Jets: Hubble Provides the Missing Key
13677 Saul Perlmutter, University of California - Berkeley See Change: Testing time-varying dark energy with z>1 supernovae and their massive cluster hosts
13690 Tanio Diaz-Santos, Universidad Diego Portales Tracking the Obscured Star Formation Along the Complete Evolutionary Merger Sequence of LIRGs
13691 Wendy L. Freedman, University of Chicago CHP-II: The Carnegie Hubble Program to Measure Ho to 3% Using Population II
13697 Vianney Lebouteiller, CEA/DSM/Irfu/Service d'Astrophysique - Laboratoire AIM Does star formation proceed differently in metal-poor galaxies?
13699 Nicolas Martin, Universite de Strasbourg I Fellowship of the Andromeda Dwarf Galaxies: A Census of their Extended Star Formation Histories
13728 Steven Kraemer, Catholic University of America Do QSO2s have Narrow Line Region Outflows? Implications for quasar-mode feedback
13733 Celine Peroux, Laboratoire d'Astrophysique de Marseille The Stellar Continuum Light from Damped Lyman-alpha Absorber Galaxies Detected with Integral Field Spectroscopy
13735 David J. Sand, Texas Tech University A New Dwarf Galaxy Associated with an Ultra-Compact High Velocity Cloud
13744 Trinh X. Thuan, The University of Virginia Green Peas and diagnostics for Lyman continuum leaking in star-forming dwarf galaxies
13754 Jeremy J. Drake, Smithsonian Institution Astrophysical Observatory The first mass and angular momentum loss measurements for a CV-like binary
13760 Derck L. Massa, Space Science Institute Filling the gap --near UV, optical and near IR extinction
13767 Michele Trenti, University of Melbourne Bright Galaxies at Hubble's Detection Frontier: The redshift z~9-10 BoRG pure-parallel survey
13773 Rupali Chandar, University of Toledo H-alpha LEGUS: Unveiling the Interplay Between Stars, Star Clusters, and Ionized Gas
13776 Michael D. Gregg, University of California - Davis Completing The Next Generation Spectral Library
13783 George G. Pavlov, The Pennsylvania State University Thermal evolution of old neutron stars
13786 Glenn Schneider, University of Arizona Decoding Debris System Substructures: Imprints of Planets/Planetesimals and Signatures of Extrinsic Influences on Material in Ring-Like Disks
13792 Rychard Bouwens, Universiteit Leiden A Complete Census of the Bright z~9-10 Galaxies in the CANDELS Data Set
13804 Kristen McQuinn, University of Minnesota - Twin Cities Important Nearby Galaxies without Accurate Distances
13816 Misty C. Bentz, Georgia State University Research Foundation High-Resolution Imaging of Active Galaxies with Direct Black Hole Mass Measurements
13833 Nicolas Tejos, University of California - Santa Cruz Characterizing the cool and warm-hot intergalactic medium in clusters at z < 0.4
13842 Frederick Hamann, University of Florida Testing the Youth and Transition Object Status of FeLoBAL Quasars
13862 Timothy M. Heckman, The Johns Hopkins University Measuring the Impact of Starbursts on the Circum-Galactic Medium
14049 C. S. Kochanek, The Ohio State University Dust to Dust: Monitoring the Evolution of the New Class of Self-Obscured Transient
14050 Laura Kreidberg, University of Chicago Exploring the Frontiers of Exoplanet Atmosphere Dynamics with NASA's Great Observatories
14062 Adam Riess, The Johns Hopkins University The Fifth and Final Epoch

Selected highlights

GO 13667: Observations of the Pluto System during the New Horizons Encounter


New Horizon image of Pluto from a distance of 65.2 million miles
Pluto, one of the largest members of the Kuiper Belt and, until recently, the outermost planet in the solar system, is the primary target of NASA's New Horizons Mission and has been the subject of a range of supporting HST programs over the past few years. Those observing programs have added four moons to the Pluto system. James Christy originally identified the largest moon, Charon, in 1978 from photographic plates Charon has a diameter of ~1200 km, or almost half that of Pluto itself. In 2005, Hubble added two small moons, christened Nix and Hydra, approximately 5,000 times fainter than Pluto itself, implying diameters as small as ~30-50 km if the surface composition is similar. More recent observations, in support of New Horizons mission, aimed to use WFC3 to search for faint rings due to dust particles that might jeopardise the space craft and require a course correction. While no rings were detected unequivocally, two small satellite, christened "P4" and "P5", have been discovered. Both are significantly fainter than Nix and Hydra, and may well be as small as 10-13 km in size. There is also some evidence that might point to the presence of a debris ring within Charon's orbit. Most recently, Hubble carried out an extensive imaging survey to identify KBOs lying beyond pluto that might seve as targets for an extended new Horizons mission. Two such candidates were identified, and Hubble will be conducting follow up observations to further constrain their orbits (Program GO 14053). The present observations are in direct support of the primary New Horizons mission. WFC3 will be used to provide a comprehensive set of direct imaging and grism observations that will provide reference data to the broad context for interpreting New Horizons data compiled during next week's system fly-by.

GO 13699: Fellowship of the Andromeda Dwarf Galaxies: A Census of their Extended Star Formation Histories


M31, the Andromeda spiral galaxy, and its companiosn - from the PANDAS survey
M31, the Andromeda galaxy, is the nearest large spiral system to the Milky Way (d ~ 700 kpc), and, with the Milky Way, dominates the Local Group. The two galaxies are relatively similar, with M31 likely the larger system; thus, Andromeda provides the best opportunity for a comparative assessment of the structural properties of the Milky Way. Like the Milky Way, Andromeda has a number of satellite galaxy companions. At present, some 31 systems have been identified, the majority from the Pan Andromeda Archaeological Survey (PANDAS), a wide-field survey utilising ground-based imaging data. The four most prominent satellites are the dwarf ellipticals NGC 147, NGC 185, NGC 205 and M32; most of the remaining systems are dwarf spheroidals, with absolute visual magnitudes between MV<\sub> =-10 and -6 and masses less than 108 MSun. The present program aims to probe the star formation history of these systems. The Advanced Camera for Surveys (ACS) will be used to obtain deep V (F606W) and I(F814W) imaging of the 19 dwarf spheroidals that currently lack any HST data; the structure of the red giant branch and horizontal branch in the resultant colour-magnitude diagrams will map the metallicity and age of the component stellar populations.
GO 13783: Thermal evolution of old neutron stars


Artist's impression of a neutron star
Neutron stars are extremely compact (~10 km diameter) massive (~1.4 to 2 solar mass) remnants of high mass (> 7 solar mass) stars. Formed during the gravitational core-collapse of Type Ib, Ic and II supernovae, they have initial temperatures exceeding 1011 Kelvon, but cool very rapidly with time. Their existence was originally proposed by Zwicky and Baade in the 1930s, but they remained unobserved until the late-1960s, when Hewish and Bell identified a pulsing radio source in the Crab nebula as a neutron star. (Hewish and Okoye had previously identified "an unusual source of high radio brightness temperature" within the crab.) Neutron stars have strong magnetic fields and rapid rotation, leading to radiation beaming along the magnetic poles; the observed pulses result from the beams sweeping across the terrestrial line of sight. Numerous pulsars are currently known, but direct observations of the neutron star's "photosphere" are much rarer. At their birth, neutron stars are extremely hot, and the initial thermal evolution can be traced by monitoring the base level X-ray flux (ie photospheric, not beamed, radiation). That method is only available for neutron stars younger than a few Myrs; older systems have cooled to the extent that the peak flux is at UV wavelengths, but those systems are also extremely faint. To date only one system has been detected at far-UV wavelengths by HST. The present program aims to use the ACS Solar Blind Camera to obtain far-UV imaging of three pulsars with ages between 17 Myrs and ~6 Gyrs, with the aim of further constraining the cooling timescales.

GO 13816: High-Resolution Imaging of Active Galaxies with Direct Black Hole Mass Measurements


Schematic diagram of an active galactic nucleus
Active galaxies are characterised by bright, compact nuclei that are the source of strong emission lines due highly ionised material. These phenomena are generally believed to arise in hot gas in an accretion disk, centred on a massive (>106 solar mass) hole; indeed, detailed kinematics for a number of objects have confirmed the presence of a compact, massive object in the core. Most active galactic nuclei (AGNs) are found in spiral galaxies that possess at least a moderately prominent bulge. These systems appear to show a correlation between radius of the boad-line region (in light days) and the total luminosity; in addition, there is an observed correlation between the mass of the black hole and the bulge luminosity. These correlations set constraints on the mechanisms underlying the formation and evolution of central black holes. As observational phenomena, they also depend critically on our ability to separate the relative contributions of the black hole system and starlight. The present proposal aims to address the latter task by obtaining high resolution HST WIFC3 images of 14 AGNs that have BLR radius measurements and back hole mass determinations from reverberation mapping. The WFC3 data will provide a moe effective method of deconvolving the relative contribution of starlight in the cenrtgal regions of the systems.

Past weeks:
page by Neill Reid, updated 11/11/2014
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