This week on HST

HST Programs: April 16 - April 22, 2012

Program Number Principal Investigator Program Title
12034 James C. Green, University of Colorado at Boulder COS-GTO: Brown Dwarf Activity Part 2
12038 James C. Green, University of Colorado at Boulder COS-GTO: COOL, WARM AND HOT GAS IN THE COSMIC WEB AND IN GALAXY HALOS Part 2
12455 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12460 Marc Postman, Space Telescope Science Institute Through a Lens, Darkly - New Constraints on the Fundamental Components of the Cosmos
12461 Adam Riess, The Johns Hopkins University Supernova Follow-up for MCT
12467 Sanchayeeta Borthakur, The Johns Hopkins University Probing ISM in the Stellar Disk of Dwarf Galaxy GQ1042+0747
12468 Keith S. Noll, NASA Goddard Space Flight Center How Fast Did Neptune Migrate? A Search for Cold Red Resonant Binaries
12472 Claus Leitherer, Space Telescope Science Institute CCC - The Cosmic Carbon Conundrum
12506 Adam L. Kraus, University of Hawaii A Precise Mass-Luminosity-Temperature Relation for Young Stars
12510 Luc Binette, Universidad Nacional Autonoma de Mexico (UNAM) Quasar Ton 34 with steepest far-UV break known has entered new bal QSO phase
12521 Xin Liu, University of California - Los Angeles The Frequency and Demographics of Dual Active Galactic Nuclei
12546 R. Brent Tully, University of Hawaii The Geometry and Kinematics of the Local Volume
12553 Johan P. U. Fynbo, University of Copenhagen, Niels Bohr Institute Detecting the stellar continuum of the galaxy counterparts of three z>2 Damped Lyman-alpha Absorbers
12564 Roeland P. van der Marel, Space Telescope Science Institute Proper Motions along the Sagittarius Stream: Constraining Milky Way Parameters and Dark Halo Shape
12567 Thomas R. Ayres, University of Colorado at Boulder Bridging STIS's Neutral Density Desert
12568 Matthew A. Malkan, University of California - Los Angeles WFC3 Infrared Spectroscopic Parallel Survey WISP: A Survey of Star Formation Across Cosmic Time
12570 Sylvain Veilleux, University of Maryland Deep FUV Imaging of Cool Cores in Galaxy Clusters
12573 Deborah Padgett, NASA Goddard Space Flight Center STIS Coronagraphy of New Debris Disks from the WISE All-Sky Survey
12582 Ariel Goobar, Stockholm University Probing the explosion environment and origin of Type Ia supernovae
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
12586 Kailash C. Sahu, Space Telescope Science Institute Detecting and Measuring the Masses of Isolated Black Holes and Neutron Stars through Astrometric Microlensing
12600 Reginald J. Dufour, Rice University Carbon and Nitrogen Enrichment Patterns in Planetary Nebulae
12602 Andrea Dieball, University of Southampton Beyond the Hydrogen-burning limit: Deep IR observations of the Globular Clusters M4
12603 Timothy M. Heckman, The Johns Hopkins University Understanding the Gas Cycle in Galaxies: Probing the Circumgalactic Medium
12612 John T. Stocke, University of Colorado at Boulder Probing Weak Intergalactic Absorption with Flaring Blazar Spectra
12659 Joaquin Vieira, California Institute of Technology Strongly Lensed Dusty Star Forming Galaxies: Probing the Physics of Massive Galaxy Formation
12668 Slawomir Stanislaw Piatek, New Jersey Institute of Technology Proper Motion Survey of Classical and SDSS Local Group Dwarf Galaxies
12685 Dean C. Hines, Space Telescope Science Institute Enabling Dark Energy Science for JWST and Beyond
12748 Martin C. Weisskopf, NASA Marshall Space Flight Center Joint Chandra and HST Monitoring of the Crab Nebula
12760 Bret Lehmer, The Johns Hopkins University DIRECT CHANDRA CONSTRAINTS ON THE EVOLUTION OF FIELD LMXB POPULATIONS

Selected highlights

GO 12461: Supernova follow-up for MCT Programs

High redshift supernovae from HST observations in previous cycles
CANDELS and CLASH are two of three Multi-Cycle Treasury Programs whose observations will be executed over HST Cycles 18, 19 and 20. Both programs have components that focus on the identification and subsequent follow-up of candidate high redshift supernovae. CLASH focuses on galaxy clusters (eg ), with 17-colour observations using ACS and WFC3. But while the cluster is centred on one camera, the second camera is being used to take deep images in fields offset by several arcminutes, and the multiple exposures obtained in those regions can be used to search for high redshift supernovae. CANDELS is a tiered wide-field imaging program that 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, those 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. CANDELS 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 existence of previous datasets permits searching for high-redshift supernovae, with the prime aim of measuring their properties at redshifts between z~1 and z~2. The present program is focused on a high-redshift candidate identifeid within the COSMOS field.

GO 12506:A Precise Mass-Luminosity-Temperature Relation for Young Stars

Artist's impression of the young, low-mass binary system, Coku Tau4
Mass, luminosity and temperature are the three of the five fundamental quantities that we'd like to know for every star (the other two are chemical composition and age, with age being the least accessible to direct measurement). Binary systems offer one of the most effective means of determining the former three parameters, where measurements of the orbital period and velocity variation permit direct determination of the system mass and, by scaling against angular measurements for visual binaries. the distance. Given the luminosity and temperature, the individual stellar radii can also be derived. These quantities are particularly useful in constraining models of young stars. The present program focuses on observations 16 low-mass systems in nearby star-forming regions. All 16 have orbital determinations, derived from AO-assisted K-band ground-based imaging. the WFC3-UVIS camera will be used to obtain multi-colour imaging, providing measurements of the spectral energy distributions of the individual components in each system, and hence estimates of the surface temperatures.

GO 12564: Proper Motions along the Sagittarius Stream: Constraining Milky Way Parameters and Dark Halo Shape

Dynamical modelling of tidal streams predicted based on the interactions between the Sagittarius dwarf and the Milky Way (from Majewski et al, 2003)
As a large spiral galaxy, the Milky Way system includes a number of satellite dwarf galaxies. The most prominent are the two Magellanic Clouds, both gas-rich, star-forming systems, with the LMC essentially a low mass, late-type spiral. Most of the remaining companions are dwarf spheroidals with old, evolved stellar populations and masses that are less than a few x 107 MSun, or 10-4 that of the Milky Way. Standing out from those systems is the Sagittarius dwarf, a system that is intermediate in mass and happens to be undergoing a merger with the Milky Way. Originally identified serendipitously from a radial velocity survey of giants towards the Galactic Bulge, subsequent observations have traced stripped remnants from the system that stretch over an almost 360-degree span. The motions of the stars in those remnants prove a particularly sensitive tracer of the overall potential of the Milky Way. The present program aims to use multi-epoch, multi-colour ACS/WFC observations to map the proper motions of stream members, determining tangential motions with an accuracy of ~ 5 km/sec.

GO 12748: Joint Chandra and HST Monitoring of the Crab Nebula

The Crab Nebula
Messier 1, the Crab Nebula, provides astronomy with one of its iconic images. The remnant of a bright supernova observed in 1054 by Arabian and Chinese astronomers, the Crab was first recorded in 1731 by the English astronomer, John Bevis, thirt-seven years before Messier compiled his catalogue of non-comets. The energy source for the gaseous emission is the neutron star that lies in the centre of nebulosity, and was one of the first pulsars to be identified. The Crab is also a source of high energy emission, including radiation at X-ray and gamma ray wavelengths. Overall, this system plays a crucial role in aiding our understanding of post-supernova evolutionary processes. However, there are still some notable undertainties in the detailed processes within even this system. In particular, in September of 2010 the Crab surprised the astronomial community by producing a powerful flare at gamma-ray wavelengths that persisted for 4 days (see GO 12381 ).A second flare of similar magnitude occurred in May, 2011. Observations taken during the 2010 flare by HST and Chandra provided some insight into the effects of the flare, but analysis was hampered by the absence of a comparison set of pre-outburst images of comparable resolution and depth. The present program aims to address that issue through coordinated monitoring of the Crab at X-ray and optical wavelengths. Tne Advanced Camera for Surveys on HST will be used to take images in the F550M filter at 6 epochs in 2012, with the observations timed to be within 10 days of X-ray images taken by Chandra using the AXAF CCD Imaging Spectrometer. These data will establish a reference set should a further flare occur.
Past weeks:
page by Neill Reid, updated 26/4/2012