|
Документ взят из кэша поисковой машины. Адрес
оригинального документа
: http://www.stsci.edu/~inr/thisweek1/2013/thisweek266.html
Дата изменения: Tue Nov 26 18:30:28 2013 Дата индексирования: Sat Mar 1 13:25:36 2014 Кодировка: Поисковые слова: п п п п п п п п п п п п п п |
| Program Number | Principal Investigator | Program Title |
|---|---|---|
| 12468 | Keith S. Noll, NASA Goddard Space Flight Center | How Fast Did Neptune Migrate? A Search for Cold Red Resonant Binaries |
| 12868 | Rodolfo Angeloni, Pontificia Universidad Catolica de Chile | Unveiling the giant jet from Sanduleak's star in the Large Magellanic Cloud |
| 12870 | Boris T. Gaensicke, The University of Warwick | The mass and temperature distribution of accreting white dwarfs |
| 12873 | Beth Biller, Max-Planck-Institut fur Astronomie, Heidelberg | Search for Planetary Mass Companions around the Coolest Brown Dwarfs |
| 12880 | Adam Riess, The Johns Hopkins University | The Hubble Constant: Completing HST's Legacy with WFC3 |
| 12884 | Harald Ebeling, University of Hawaii | A Snapshot Survey of The Most Massive Clusters of Galaxies |
| 12887 | Susan D. Benecchi, Planetary Science Institute | Precise Orbit Determination for New Horizons Candidate KBOs |
| 12921 | Yangsen Yao, Eureka Scientific Inc. | Multiwavelength Spectroscopy of the Interstellar Medium: O and Ne Abundance ratio |
| 12923 | Andras Gaspar, University of Arizona | Pointing the Finger: Calibrating the Hidden Features of STIS and Enabling New Coronagraphy at Separations of 0.15'' |
| 12939 | Elena Sabbi, Space Telescope Science Institute - ESA | Hubble Tarantula Treasury Project {HTTP: unraveling Tarantula's web} |
| 12961 | Misty C. Bentz, Georgia State University Research Foundation | A Cepheid Distance to NGC6814 |
| 12966 | Roeland P. van der Marel, Space Telescope Science Institute | The Nature of Dark Matter: Halo Cusps or Cores from dSph internal proper motion dynamics |
| 12967 | Abhijit Saha, National Optical Astronomy Observatory, AURA | Establishing a Network of DA White Dwarf SED Standards |
| 12969 | Peter Garnavich, University of Notre Dame | Global Properties Are Not Enough: Probing the Local Environments of Type Ia Supernovae |
| 12970 | Michael C. Cushing, University of Toledo | Completing the Census of Ultracool Brown Dwarfs in the Solar Neighborhood using HST/WFC3 |
| 12995 | Christopher Johns-Krull, Rice University | Testing Disk Locking in the Orion Nebula Cluster |
| 12998 | Deborah Padgett, NASA Goddard Space Flight Center | STIS Coronagraphy of Bright New Debris Disks from the WISE All-Sky Survey |
| 13003 | Michael D. Gladders, University of Chicago | Resolving the Star Formation in Distant Galaxies |
| 13009 | Guido De Marchi, European Space Agency - ESTEC | Studying pre-main sequence stars across the metallicity ladder |
| 13024 | John S. Mulchaey, Carnegie Institution of Washington | A Public Snapshot Survey of Galaxies Associated with O VI and Ne VIII Absorbers |
| 13057 | Kailash C. Sahu, Space Telescope Science Institute | Detecting and Measuring the Masses of Isolated Black Holes and Neutron Stars through Astrometric Microlensing |
| 13116 | Preeti Kharb, Indian Institute of Astrophysics, Bangalore | Probing The Causes of the High/Low Jet Power Dichotomy in AGN Jets with Chandra and HST |
| 13176 | Daniel Apai, University of Arizona | Extrasolar Storms: The Physics and Chemistry of Evolving Cloud Structures in Brown Dwarf Atmospheres |
| 13177 | Marusa Bradac, University of California - Davis | Spitzer UltRaFaint SUrvey {SURF'S Up}: Cluster Lensing and Spitzer Extreme Imaging Reaching Out to z~7 |
| 13282 | You-Hua Chu, University of Illinois at Urbana - Champaign | A Search for Surviving Companions of Type Ia Supernovae in the Large Magellanic Cloud |
| 13334 | Adam Riess, The Johns Hopkins University | The Longest Period Cepheids, a bridge to the Hubble Constant |
| 13355 | Bruce McCollum, Catholic University of America | Uncovering the Nature of the Evolving Remnant Star of a Recent Stellar Merger |
| 13475 | David Jewitt, University of California - Los Angeles | Hubble Imaging of a Newly Discovered Main Belt Comet |
| 13476 | Nitya Kallivayalil, The University of Virginia | Proper Motion and Internal Kinematics of the SMC: are the Magellanic Clouds bound to one another? |
GO 12887: Precise Orbit Determination for New Horizons Candidate KBOs
Hubble Space Telescope images of the Pluto system, including the recently discovered moons, P4 and P5 |
The Kuiper Belt lies beyond the orbit of Neptune, extending from ~30 AU to ~50 AU from the Sun, and includes at least 70,000 objects with diameters exceeding 100 km. Setting aside Pluto, the first trans-Neptunian objects were discovered in the early 1990s. Most are relatively modest in size, with diameters of a few hundred km and photometric properties that suggested an icy composition, similar to Pluto and its main satellite, Charon. Over the last three years, however, a handful of substantially larger bodies have been discovered, with diameters of more than 1000 km; indeed, one object, Eris (2003 UB13), is slightly larger than Pluto (2320 km) and 25% more massive. We know the mass for Eris because it has a much lower mass companion, Dysnomia, which orbits Eris with a period of 16 days (see this recent press release ). Pluto, itself, has at least 5 companions: Charon, which is about 1/7th the mass of Pluto, and the much smaller bodies, Hydra, Nix, P4 and P5 discovered through HST observations within the last few years. The New Horizons Mission was launched on January 19th 2006 with the prime purpose of providing the first detaikled examination of Pluto, one of the largest members of the Kuiper Belt and, until recently, the outermost planet in the solar system. Following the Pluto fly-by, set for Bastille day in 2015, New Horizons will be redirected towards one or more smaller members of the Kuiper Belt, with the aim of providing a closer look at these icy bodies. The present program aims to use HST for astrometric observations of potential targets, with the goal of refining the orbits. |
ACS images of galaxy-galaxy Einstein ring lenses from the Sloan survey |
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 both to investigate the mass distribution of individual foreground galaxies and to probe the properties of more distant systems. 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. Moreover, the lensed image of the background galaxy is not only amplified, but expanded in angular size, enabling much more detailed investigation of the properties of such systems than in un-lensed field galaxies at the same redshift. The present program is capitalising on galaxy-galaxy lenses as natural telescopes to probe star formation at redshifts z>1. WFC3 is being used to observe 73 galaxy-galaxy lensed systems identified from the Sloan Digital Sky Survey. The systems are imaged in both the UVIS and IR channels, mapping the unrerlying spectral energy distribution, and hence the star formation rate, as a function of location in the background galaxies. |
GO 13057: Detecting and Measuring the Masses of Isolated Black Holes and Neutron Stars through Astrometric Microlensing
A rather spectacular version of black hole lensing. |
Gravitational lensing is a consequence of general relativity. Its effects were originally quantified by Einstein himself in the mid-1920s. In the 1930s, Fritz Zwicky suggested that galaxies could serve as lenses, but lower mass objects can also also lens background sources. Bohdan Paczynski pointed out in the mid-1980s that this offered a means of detecting dark, compact objects that might contribute to the dark-matter halo. Paczcynski's suggestion prompted the inception of several large-scale lensing surveys, notably MACHO, OGLE, EROS and DUO. Those wide-field imaging surveys have target high density starfields towards the Magellanic Clouds and the Galactic Bulge, and have succeeded in identifying numerous lensing events. The duration of each event depends on several factors, including the tangential motion of the lens and its mass. Long-term events are generally associated with a massive lens. Duration alone is not sufficient to identify a lens as a black hole - a source with very low tangential motion relative to the Sun can produce the same effect. However, microlensing not only leads to flux amplification, but also to small astrometric motions, caused by the appearance and disappearance of features in the lensed light. Those motions serve as a mass discriminant - higher mass lenses produce larger amplitude motions. The expected astrometric signal from a black hole lens is > 1.4 millarcseconds, just measureable with HST. This program aims to capitalise on this fact by searching for lensing by black holes in the Galactic field. The observations target long-duration lensing events in the Galactic Bulge. |
GO 13476: Proper Motion and Internal Kinematics of the SMC: are the Magellanic Clouds bound to one another?
The Large Magellanic Cloud (upper left) with the Small Magellanic Cloud (right)
and the (foreground) Galactic globular cluster47 Tucanae
|
The Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC) are the most massive satellites of the Milky Way galaxy. The orbital motions of these systems can be used to probe the mass distribution of Milky Way, and backtracking the orbits can shed light on how the three systems have interacted, In particular, the well known Magellanic Stream, stretching between the two Clouds, is thought to be a product either of interactions between the Clouds, or of ram-stripping of gas from the LMC on its last passage through the Plane of the Milky Way. Understanding the full scope of the interactions demands knowledge of the tangential motions of these systems - that is, proper motion measurements. Given the distances of the Clouds (~50 kpc.), the actual motions amount to only a few milliarcseconds, but the high spatial resolution and high stability of HST imaging makes such measurements possible. Past observing programs (eg GO 11730) have concentrated on the LMC, using the now-defunct ACS High Resolution Camera (ACS/HRC), the Planetary Camera on WFPC2 and the UVIS camera on WFC3 to target known QSOs lying behind the Clouds; the QSOs serve as fixed reference points for absolute astrometry of the numerous foreground LMC/SMC stars. The present program aims to build on those results by targeting 30 newly identified QSos behind the SMC for WFC3 observations ove a two-year span. The new observations should enable astronomers to not only refine the mean motion of the SMC, but also probe the internal rotation and velocity dispersion of stars in the Small Cloud. |