This week on HST

HST Programs: December 3 - December 9, 2012

Program Number Principal Investigator Program Title
12034 James C. Green, University of Colorado at Boulder COS-GTO: Brown Dwarf Activity Part 2
12109 Julianne Dalcanton, University of Washington A Panchromatic Hubble Andromeda Treasury - I
12111 Julianne Dalcanton, University of Washington A Panchromatic Hubble Andromeda Treasury - I
12471 Dawn K. Erb, University of Wisconsin - Milwaukee The Bottom of the Iceberg: Faint z~2 Galaxies and the Enrichment of the IGM
12488 Mattia Negrello, Open University SNAPshot observations of gravitational lens systems discovered via wide-field Herschel imaging
12528 Philip Massey, Lowell Observatory Probing the Nature of LBVs in M31 and M33: Blasts from the Past
12568 Matthew A. Malkan, University of California - Los Angeles WFC3 Infrared Spectroscopic Parallel Survey WISP: A Survey of Star Formation Across Cosmic Time
12575 Anthony H. Gonzalez, University of Florida New Constraints on Intragroup Light and the Baryon Budget in Galaxy Groups
12595 Michael Eracleous, The Pennsylvania State University Unraveling the LINER Conspiracy
12662 Oleg Y. Gnedin, University of Michigan Hypervelocity Stars as Unique Probes of the Galactic Center and Outer Halo
12788 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12813 Brian Schmidt, Australian National University Network of 13 high precision STIS spectrophotometric standards for ground based surveys
12861 Xiaohui Fan, University of Arizona Morphologies of the Most UV luminous Lyman Break Galaxies at z~3
12866 Mark Swinbank, University of Durham A Morphological Study of ALMA Identified Sub-mm Galaxies with HST/WFC3
12870 Boris T. Gaensicke, The University of Warwick The mass and temperature distribution of accreting white dwarfs
12884 Harald Ebeling, University of Hawaii A Snapshot Survey of The Most Massive Clusters of Galaxies
12903 Luis C. Ho, Carnegie Institution of Washington The Evolutionary Link Between Type 2 and Type 1 Quasars
12928 Alaina L. Henry, Oak Ridge Associated Universities Gaseous outflows from low mass galaxies: Understanding local laboratories for high redshift star formation
12939 Elena Sabbi, Space Telescope Science Institute - ESA Hubble Tarantula Treasury Project {HTTP: unraveling Tarantula's web}
12940 Philip Massey, Lowell Observatory The Unevolved Massive Star Content of the Magellanic Clouds
12969 Peter Garnavich, University of Notre Dame Global Properties Are Not Enough: Probing the Local Environments of Type Ia Supernovae
12982 Nicolas Lehner, University of Notre Dame Are the Milky Way's High Velocity Clouds Fuel for Star Formation or for the Galactic Corona?
12996 Christopher Johns-Krull, Rice University Exploring the Role of Stellar Magnetic Fields in Accretion and Outflows from Young Stars using the Hot Emission Lines of Herbig Ae/Be Stars
13003 Michael D. Gladders, University of Chicago Resolving the Star Formation in Distant Galaxies
13017 Timothy M. Heckman, The Johns Hopkins University UV Spectroscopy of Lyman Break Galaxy Analogs: A Local Window on the Early Universe
13025 Andrew J. Levan, The University of Warwick Unveiling the progenitors of the most luminous supernovae
13029 Alex V. Filippenko, University of California - Berkeley A Snapshot Survey of the Sites of Recent, Nearby Supernovae
13033 Jason Tumlinson, Space Telescope Science Institute COS-Halos: New FUV Measurements of Baryons and Metals in the Inner Circumgalactic Medium
13046 Robert P. Kirshner, Harvard University RAISIN: Tracers of cosmic expansion with SN IA in the IR
13048 Jay Strader, Michigan State University The First Unambiguous Detection of a Distinct Metal-poor Stellar Halo in a Massive Early-type Galaxy

Selected highlights

GO 12105, 12107: A Panchromatic Hubble Andromeda Treasury

M31: the Andromeda spiral galaxy
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. Moreover, while M31 is (obviously) more distant, our external vantage point can provide crucial global information that complements the detailed data that we can acquire on individual members of the stellar populations of the Milky Way. With the advent on the ACS and, within the last 2 years, WFC3 on HST, it has become possible to resolve main sequence late-F and G dwarfs, permitting observations that extend to sub-solar masses in M31's halo and disk. Initially, most attention focused on the extended halo of M31 (eg the Cycle 15 program GO 10816 ), with deep imaging within a limited number of fields revealing the complex metallicity structure within that population. With the initiation of the present Multi-Cycle Treasury program, attention switches to the M31 disk. "PHAT" is conducting a multi-waveband survey of approximately one third of disk and bulge, focusing on the north-east quadrant. Observations have been taken over Cycles 18, 19 and 20, and are providing a thorough census of upper main-sequence stars, open clusters, associations and star forming regions, matching the stellar distribution against the dust and gas distribution.
GO 12283/12568: WISP - A Survey of Star Formation Across Cosmic Time

A region of massive star formation
Star formation is the key astrophysical process in determining the overall evolution of galactic systems, the generation of heavy elements, and the overall enrichment of interstellar and intergalactic material. Tracing the overall evolution through a wide redshift range is crucial to understanding how gas and stars evolved to form the galaxies that we see around us now. The present program builds on the ability of HST to carry out parallel observations, using more than one instrument. While the Cosmic Origins Spectrograph is focused on obtaining ultraviolet spectra of unparalleled signal-to-noise, this program uses the near-infrared grisms mounted on the Wide-Field Camera 3 infrared channel to obtain low resolution spectra between 1 and 1.6 microns of randomly-selected nearby fields. The goal is to search for emission lines characteristic of star-forming regions. In particular, these observations are capable of detecting Lyman-alpha emission generated by star formation at redshifts z > 5.6. A total of up to 40 "deep" (4-5 orbit) and 20 "shallow" (2-3 orbit) fields will be targeted in the course of this observing campaign.

GO 12662: Hypervelocity Stars as Unique Probes of the Galactic Center and Outer Halo

Artist's impression of a hypervelocity star
Hypervelocity stars are stars that have velocities that exceed the escape velocity of the Milky Way by a very substantial margin. Stars can only achieve such velocities through violent gravitational interactions with other bodies. Indeed, to achieve velocities of 1,000 km/sec or more, the proposed mechanism involves binary stars interacting with the black hole at the Galactic Centre: one of the binary components is lost to the black hole, and the other ejected at from the core. The existence of such objects was hypothesised over 20 years ago, but the first candidate was only identified in 2005: SDSS J090745.0+024507, an apparently non-descript sunlike star, lying at a distance of 71 kpc from the Sun in the Galactic, and moving at a velocity of 850 km/sec, or more than twice the escape velocity. Since then, a number of other candidates have been identified. HST was used to image 11 stars in Cycle 17 (GO 11589); the present program will obtain follow-up imaging, permitting the determination of precise proper motions, and hence space velocities, for these unusual stars.

GO 12870: The mass and temperature distribution of accreting white dwarfs

An accreting white dwarf starn in a close binary system
Supernovae are the most spectacular form of stellar obituary. Since B2FH, the physical processes underlying their eruptive deaths have been known to play a key role in populating the ISM with metals beyond the iron peak. More recently, these celestial explosions have acquired even greater significance through the use of Type Ia supernovae as distance indicators in mapping the `dark energy' acceleration term of cosmic expansion. However, while there are well-established models for the two main types of supernovae (runaway fusion on the surface of a white dwarf in a binary system for Type Ia, or detonation of the core in Type II), some significant uncertainties remain concerning the physical details of the disruption, and, potentially, the overall uniformity of these events. Consequently, there is potential for systematic bias in the distance estimates. The present program aims to set constraints on the various mechanisms associated with white dwarf stars by investigating the rotational properties of over 40 degenerate companions in catclysimic variable systems. All of these systems are in the process of accreting material from the companion star, as the latter voerflows its Roche lobes. The program aims to obtain ultraviolet spectra with the Cosmic origins Spectrograph, probing both the spin rates and the orbital parameters. Over the next decade, these data may lead to the determinaton of reliable masses for both stars once accurate parallax measurements become available from Gaia.

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