This week on HST


HST Programs: January 30 - February 5, 2012


Program Number Principal Investigator Program Title
12025 James C. Green, University of Colorado at Boulder COS-GTO: QSO Absorbers, Galaxies and Large-scale Structures in the Local Universe Part 2
12106 Julianne Dalcanton, University of Washington A Panchromatic Hubble Andromeda Treasury - I
12110 Julianne Dalcanton, University of Washington A Panchromatic Hubble Andromeda Treasury - I
12177 Pieter van Dokkum, Yale University 3D-HST: A Spectroscopic Galaxy Evolution Treasury
12178 Scott F. Anderson, University of Washington Spanning the Reionization History of IGM Helium: a Highly Efficient Spectral Survey of the Far-UV-Brightest Quasars
12181 Drake Deming, University of Maryland The Atmospheric Structure of Giant Hot Exoplanets
12210 Adam S. Bolton, University of Utah SLACS for the Masses: Extending Strong Lensing to Lower Masses and Smaller Radii
12236 Lisa Glass, Dominion Astrophysical Observatory The Nuclear to Global Connection: a Detailed View of Compact Stellar Nuclei in a Complete Sample of Virgo Ellipticals
12248 Jason Tumlinson, Space Telescope Science Institute How Dwarf Galaxies Got That Way: Mapping Multiphase Gaseous Halos and Galactic Winds Below L*
12283 Matthew A. Malkan, University of California - Los Angeles WFC3 Infrared Spectroscopic Parallel Survey {WISP}: A Survey of Star Formation Across Cosmic Time
12304 Jon A. Holtzman, New Mexico State University Metallicity distribution functions of 4 Local Group dwarf galaxies
12310 Goeran Oestlin, Stockholm University LARS - The Lyman Alpha Reference Sample
12319 Slawomir Stanislaw Piatek, New Jersey Institute of Technology Proper Motion Survey of Classical and SDSS Local Group Dwarf Galaxies
12440 Sandra M. Faber, University of California - Santa Cruz Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey -- GOODS-South Field, Non-SNe-Searched Visits
12453 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12454 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12474 Boris T. Gaensicke, The University of Warwick The frequency and chemical composition of rocky planetary debris around young white dwarfs
12476 Kem Cook, Eureka Scientific Inc. Measuring the Hubble Flow Hubble Constant
12488 Mattia Negrello, Open University SNAPshot observations of gravitational lens systems discovered via wide-field Herschel imaging
12504 Michael C. Liu, University of Hawaii Bridging the Brown Dwarf/Jupiter Temperature Gap with a Very Cold Brown Dwarf
12514 Karl Stapelfeldt, NASA Goddard Space Flight Center Imaging of Newly-identified Edge-on Protoplanetary Disks in Nearby Star-Forming Regions
12546 R. Brent Tully, University of Hawaii The Geometry and Kinematics of the Local Volume
12572 Michele Trenti, University of Colorado at Boulder The Brightest of Reionizing Galaxies Pure Parallel Survey
12585 Sara Michelle Petty, University of California - Los Angeles Unveiling the Physical Structures of the Most Luminous IR Galaxies Discovered by WISE at z>1.6
12594 Edmund Nelan, Space Telescope Science Institute The White Dwarf Mass-Radius Relation Based on Dynamical Masses: STIS Observations of Close Double Degenerates
12614 Orly Gnat, California Institute of Technology Are the Ultra-Compact High-Velocity Clouds Minihalos? Constraints from Quasar Absorption Lines
12659 Joaquin Vieira, California Institute of Technology Strongly Lensed Dusty Star Forming Galaxies: Probing the Physics of Massive Galaxy Formation

Selected highlights

GO 12178: Spanning the Reionization History of IGM Helium: a Highly Efficient Spectral Survey of the Far-UV-Brightest Quasars


GALEX image of the nearby spiral, M81
The reionisation epoch for intergalactic helium is thought to occur somewhere between redshifts 3 and 4. Observations with the GALEX satellite, a NASA small explorer-class mission equipped with a 50-cm diameter telescope, are proving critical in testing this hypothesis through the identification of UV bright quasars in the appropriate redshift range. Galex was launched on 28th April 2003, and continues to operate more than 30 months beyond its nominal lifetime, conducting ultraviolet imaging and low-resolution grism spectroscopy at far-UV (125-175 nm) and near-UV (175-280 nm) wavelengths. Past HST programs by this research have used the ACS/SBC to target sources identified by cross-referencing GALEX against SDSS catalogues of moderate (1 < z < 3) and high redshift (z > 3.1) quasars. These sources can serve as effective probes of the ionisation state of the intergalactic medium at intervening redshifts. In particular, analysis of the He II Lyman-alpha absorption will shed light on the epoch of reionisation of intergalactic helium, generall placed between redshifts 3 and 4. The present program will use the ACS/SBC PR120L prism for spectroscopy of 40 QSOs with redshifts in the range 3.1 < z < 5.1.

GO 12440: Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey -- GOODS-South Field, Non-SNe-Searched visits


Part of the GOODS/Chandra Deep Field South field, as imaged by HST
CANDELS is one of three Multi-Cycle Treasury Program, whose observations will be executed over the next three HST Cycles. It builds on past investment of both space- and ground-based observational resources. In particular, it includes coverage of the two fields of the Great Observatory Origins Deep Survey (GOODS), centred on the northern Hubble Deep Field (HDF) in Ursa Major and the Chandra Deep Field-South in Fornax. In addition to deep HST data at optical and near-infrared wavelengths, the fields have been covered at X-ray wavelengths by Chandra (obviously) and XMM-Newton; at mid-infrared wavelengths with Spitzer; and ground-based imaging and spectroscopy using numerous telescopes, including the Kecks, Surbaru and the ESO VLT. This represents an accumulation of almost 1,000 orbits of HST time, and comparable scale allocations on Chandra, Spitzer and ground-based facilities. The CANDELS program is capitalising on this large investment, with new observations with WFC3 and ACS on both GOODS fields, and on three other fields within the COSMOS, EGS and UDS survey areas (see this link for more details). The prime aims of the program are twofold: reconstructing the history of galaxy formation, star formation and nuclear galactic activity at redshifts between z=8 and z=1.5; and searching for high-redshift supernovae to measure their properties at redshifts between z~1 and z~2. The program incorporates a tiered set of observations that complement, in areal coverage and depth, the deep UDF observations, while the timing of a subset of the observations will be set to permit detection of high redshift SNe candidates, for subsequent separate follow-up.

GO 12504: Bridging the Brown Dwarf/Jupiter Temperature Gap with a Very Cold Brown Dwarf


The very low-mass binary system, CFBDSIR J1458+10AB
Brown dwarfs are objects that form in the same manner as stars, by gravitational collapse within molecular clouds, but which failt to accrete sufficient mass to raise the central temperature above ~2 million Kelvin and ignite hydrogen fusion.In consequence, these objects, which at solar abundances have masses less than 0.075 MSun or ~75 M<\sub>Jup, lack a sustained source of energy, and cool and fade on relatively short astronomical (albeit, long anthropological) timescales. Following their discovery over a decade ago, considerable observational and theoretical attention has focused on the evolution of their intrinsic properties, particularly the details of the atmospheric changes. At their formation, most brown dwarfs have temperatures of ~3,000 to 3,500K, comparable with early-type M dwarfs, but they rapidly cool, with the rate of cooling increasing with decreasing mass. As temperatures drop below ~2,000K, dust condenses within the atmosphere, molecular bands of titanium oxide and vanadium oxide disappear from the spectrum to be replaced by metal hydrides, and the obejcts are characterised as spectral type L. Below 1,300K, strong methane bands appear in the near-infrared, characteristics of spectral type T. At lower temperatures, other species, notably ammonia, are expected to become prominent, and attempts are currently under way to find examples of these "Y" dwarfs. The search is complicated by the fact that such objects are extremely faint instrinsically, so only the nearest will be detectable. Wide-field surveys have been undertaken at infrared wavelengths with both ground-based telescopes (eg UKIDDS) and satellite observatories (eg WISE). However, an alternative approach is to "look uner the lamp-post": both stars and brown dwarfs are often found as binary or multiple systems, so one can take a sample of low-mass obejcts known to be within the Solar Neighbourhood, and look for even lower luminosity companions. That technique served in the past to identify van Biesbroeck 10, the first ultracool dwarf; GD 165B, the first L dwarf; and Gl 229B, the first T dwarf. The prime target of this proposal, CFBDSIR J1458+10B, was found in a similar manner, through deep infrared imaging targetting known nearby ultracool dwarfs. The primary, a ~T9 dwarf, was discovered in the course of the Canada-France Brown Dwarf Survey survey (hence CFBDS), lies at a distance of ~23 parsecs, has a luminosity of ~10-6 LSun and a temperature around 550K. The secondary was uncovered at a separation of 0.11 arcseconds through Keck laser AO imaging, is 2 magnitudes fainter than the primary at H, has a luminosity of ~2 x 10-7 LSun and is the coolest brown dwarf currently known, with a surface temperature estimated as only 370 K, comparable with boiling water. HST will be used to obtain far-red and near-infrared photometry, with the aim of better characterising the spectral energy distribution at those wavelengths.

GO 12572: The Brightest of Reionizing Galaxies Pure Parallel Survey


The ACS optical/far-red image of the Hubble Ultra Deep Field
Galaxy evolution in the early Universe is a discipline of astronomy that has been transformed by observations with the Hubble Space Telescope. The original Hubble Deep Field, the product of 10 days observation in December 1995 of a single pointing of Wide Field Planetary Camera 2, demonstrated conclusively that galaxy formation was a far from passive process. The images revealed numerous blue disturbed and irregular systems, characteristic of star formation in galaxy collisions and mergers. Building on this initial progam, the Hubble Deep Field South (HDFS) provided matching data for a second southern field, allowing a first assessment of likely effects due to field to field cosmic variance, and the Hubble Ultra-Deep Field (UDF) probed to even fainter magitude with the Advanced Camera for Surveys (ACS). The highest redshift objects found in the UDF have redshifts approaching z~7. Pushing to larger distances, and greater ages, demands observatons at near-infrared wavelengths, as the characteristics signatures of star formation are driven further redward in the spectrum. Wide Field Camera 3, installed in Servicing Mission 4, is well suited to these observations, and a number of programs are in place in Cycle 19 that address these issues. Indeed, WFC3 is employed in pure parallel mode by several programs. These take advantage of other science programs, usually with COS, that involve 2-5 orbit pointings on sources at high galactic latitude. The WFC3 pointing is unplanned, since it depends on the orientation adopted for the prime observations, but 2-5 orbits of IR imaging can reach galaxies at redshifts exceeding z=7 (potentially even z~8) in high latitude field.

Past weeks:
page by Neill Reid, updated 26/1/2012