This week on HST

HST Programs: November 23 - November 29, 2009

Program Number Principal Investigator Program Title Links
11548 S. Thomas Megeath, University of Toledo NICMOS Imaging of Protostars in the Orion A Cloud: The Role of Environment in Star Formation Abstract
11565 Sebastien Lepine, American Museum of Natural History A search for astrometric companions to very low-mass, Population II stars Abstract
11577 Brad C. Whitmore, Space Telescope Science Institute Opening New Windows on the Antennae with WFC3 Abstract
11579 Alessandra Aloisi, Space Telescope Science Institute The Difference Between Neutral- and Ionized-Gas Metal Abundances in Local Star-Forming Galaxies with COS Abstract
11583 Joel N. Bregman, University of Michigan The Star Formation Rate In Nearby Elliptical Galaxies Abstract
11588 Raphael Gavazzi, CNRS, Institut d'Astrophysique de Paris Galaxy-Scale Strong Lenses from the CFHTLS survey Abstract
11594 John M. O'Meara, Saint Michaels College A WFC3 Grism Survey for Lyman limit absorption at z=2 Abstract
11599 Richard A. Wade, The Pennsylvania State University Distances of Planetary Nebulae from SNAPshots of Resolved Companions Abstract
11603 Jennifer Andrews, Louisiana State University and A & M College A Comprehensive Study of Dust Formation in Type II Supernovae with HST, Spitzer and Gemini Abstract
11644 Michael E. Brown, California Institute of Technology A dynamical-compositional survey of the Kuiper belt: a new window into the formation of the outer solar system Abstract
11657 Letizia Stanghellini, National Optical Astronomy Observatories The population of compact planetary nebulae in the Galactic Disk Abstract
11661 Misty C. Bentz, University of California - Irvine The Black Hole Mass - Bulge Luminosity Relationship for the Nearest Reverberation-Mapped AGNs Abstract
11690 Brian R. Espey, University of Dublin, Trinity College EG And: Providing the Missing Link Required for Modelling Red Giant Mass-loss Abstract
11696 Matthew A. Malkan, University of California - Los Angeles Infrared Survey of Star Formation Across Cosmic Time Abstract
11697 Slawomir Stanislaw Piatek, New Jersey Institute of Technology Proper Motion Survey of Classical and SDSS Local Group Dwarf Galaxies Abstract
11704 Brian Chaboyer, Dartmouth College The Ages of Globular Clusters and the Population II Distance Scale Abstract
11714 Howard E. Bond, Space Telescope Science Institute Snapshot Survey for Planetary Nebulae in Local Group Globular Clusters Abstract
11720 Patrick Dufour, University of Arizona Detailed analysis of carbon atmosphere white dwarfs Abstract
11723 Robert A. Fesen, Dartmouth College Imaging the Crab Nebula-Like Supernova Remnant 3C 58 Abstract
11724 Marla C. Geha, Yale University Direct Age Determination of the Local Group dE Galaxies NGC 147 and NGC 185 Abstract
11735 Filippo Mannucci, INAF - IRA, Firenze The LSD project: dynamics, merging and stellar populations of a sample of well-studied LBGs at z~3 Abstract
11788 George Fritz Benedict, University of Texas at Austin The Architecture of Exoplanetary Systems Abstract

Selected highlights

GO 11548: NICMOS Imaging of Protostars in the Orion A Cloud: The Role of Environment in Star Formation

An image of the orion Nebula superimposed on the 13CO map of Orion A (from this link ). The Orion association is the largest nearby star-forming complex, providing a key laboratory for unlocking the secrets of star formation. As such, it has been subject to intense scrutiny at all wavelengths from both ground and space. Surveys at near-infrared and mid-infrared wavelenths, notably by Spitzer, have identified an extensive number of embedded sources, young stellar objects (YSOs) that are still accreting from the surrounding molecular gas. This proposal focuses on 252 sources within the Orion A molecular cloud, the complex that includes the Orion Nebula Cluster. In the original Cycle 16 incarnation of this program, NICMOS was used to survey a subset of the protostars; the program has since been transferred to the WFC3-IR camera. The observations are an excellent complement to Spitzer since, while HST cannot offer either the same areal coverage or sensitivity at mid-infrared wavelegths, the camera can provide a resolution close to 0.1 arcsecond, an order of magnitude higher than the Spitzer images.

GO 11588: Galaxy-Scale Strong Lenses from the CFHTLS survey

ACS images of galaxy-galaxy Einstein ring lenses Gravitational lensing is a consequence the theory of general relativity. Its importance as an astrophysical tool first became apparent with the realisation (in 1979) that the quasar pair Q0957+561 actually comprised two lensed images of the same background quasar. In the succeeding years, lensing has been used primarily to probe the mass distribution of galaxy clusters, using theoretical models to analyse the arcs and arclets that are produced by strong lensing of background galaxies, and the large-scale mass distribution, through analysis of weak lensing effects on galaxy morphologies. Gravitational lensing can also be used to investigate the mass distribution of individual galaxies. Until recently, the most common background sources were quasars. Galaxy-galaxy lenses, however, offer a distinct advantage, since the background source is extended, and therefore imposes a stronger constraints on the mass distribution of the lensing galaxy than a point-source QSO. The CFHT Legacy survey was a concerted effort by Canada and France to use almost half of their dark/grey time on the Canada-France-Hawaii telescope to obtain deep images with the MegaCam 1x1 degree imager. In ttoal, about 450 nights were devoted to this project between mid-2003 and early 2009, covering almost 600 square degrees to varying depths. The resultant survey provides a powerful means for identifying candidate galaxy-galaxy lenses. This program is using WFC3 SNAP imaging to verify the nature of those candidates, and provide the angular resolution necessary to model the mass distribution.

GO 11599: Distances of Planetary Nebulae from SNAPshots of Resolved Companions

HST image of the Eskimo planetary nebula, NGC 2392 Planetary nebulae are the spectacular results of the penultiumate evoutionary phase of intermediate-mass stars. Towards the conclusion of the second, or asymptotic, giant branch, ~1 to ~7 solar mass stars have achieved radii exceeding 100 RSun and their extensive envelopes are subject to long-period, opacity-driven pulsations and substantial mass loss. AGB evolution terminates with the ejection of the stellar envelope, revealing the bare core, with an initial surface temperature approaching 100,000K. The core cools to become a white dwarf but, during the initial phase, its luminosity is sufficient to excite gases in the expanding envelope, producing a planetary nebula. These objects are extremely spectacular, but also, in Galactic terms, rare. As a result, we only know reliable distances to a handful of such systems. The present program aims to tackle this issue through observations of planetary nebulae with known or suspected lower-mass companions. Once confirmed as binaries, distances can be estimated using the companions, which still reside on the main sequence.

Past weeks:
page by Neill Reid, updated 23/10/2009