Search Publications
A Search for Binary Systems among the Nearest L Dwarfs
Burgasser, Adam J.; Reid, I. Neill; Cruz, Kelle L. +2 more
We have used the Near-Infrared Camera and Multi-Object Spectrometer NIC1 camera on the Hubble Space Telescope to obtain high angular resolution images of 52 ultracool dwarfs in the immediate solar neighborhood. Nine systems are resolved as binary, with component separations from 1.5 to 15 AU. Based on current theoretical models and empirical bolom…
Spitzer 70 and 160 µm Observations of the Extragalactic First Look Survey
Im, M.; Frayer, D. T.; Surace, J. A. +33 more
We present 70 and 160 µm observations from the Spitzer extragalactic First Look Survey (xFLS). The data reduction techniques and the methods for producing co-added mosaics and source catalogs are discussed. Currently, 26% of the 70 µm sample and 49% of the 160 µm-selected sources have redshifts. The majority of sources with redsh…
The Host Galaxies of Narrow-Line Seyfert 1 Galaxies: Nuclear Dust Morphology and Starburst Rings
Kraemer, S. B.; Crenshaw, D. M.; Deo, R. P.
We present a study of the nuclear morphology of a sample of narrow- and broad-line Seyfert 1 galaxies (NLS1s and BLS1s, respectively) based on broadband images in the Hubble Space Telescope archives. In our previous study we found that large-scale stellar bars at >1 kpc from the nucleus are more common in NLS1s than BLS1s. In this paper we find…
Hubble Space Telescope ACS Wide-Field Photometry of the Sombrero Galaxy Globular Cluster System
Spitler, Lee R.; Forbes, Duncan A.; Brodie, Jean P. +3 more
A detailed imaging analysis of the globular cluster (GC) system of the Sombrero galaxy (NGC 4594) has been accomplished using a six-image mosaic from the Hubble Space Telescope Advanced Camera for Surveys. The quality of the data is such that contamination by foreground stars and background galaxies is negligible for all but the faintest 5% of the…
RR Lyrae Variables in M33. I. Evidence for a Field Halo Population
Sarajedini, Ata; Schommer, Robert; Barker, M. K. +2 more
We present observations of RR Lyrae variables in the Local Group late-type spiral galaxy M33. Using the Advanced Camera for Surveys on the Hubble Space Telescope, we have identified 64 ab-type RR Lyrae stars in M33. We have estimated reddenings for these stars based on their minimum light V-I colors and metallicities based on their periods. From t…
Spectroscopic Metallicities for Fornax Ultracompact Dwarf Galaxies, Globular Clusters, and Nucleated Dwarf Elliptical Galaxies
Infante, L.; Hilker, M.; Jordán, A. +1 more
Various formation channels for the puzzling ultracompact dwarf galaxies (UCDs) have been proposed in the last few years. To better judge some of the competing scenarios, we present spectroscopic [Fe/H] estimates for a sample of 26 compact objects in the central region of the Fornax Cluster, covering the magnitude range of UCDs and bright globular …
Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. IV. Measurement for Sculptor
Minniti, Dante; Mateo, Mario; Piatek, Slawomir +5 more
This article presents a measurement of the proper motion of the Sculptor dwarf spheroidal galaxy determined from images taken with the Hubble Space Telescope using the Space Telescope Imaging Spectrograph in the imaging mode. Each of two distinct fields contains a quasi-stellar object that serves as the ``reference point.'' The measured proper mot…
Orbits and Photometry of Pluto's Satellites: Charon, S/2005 P1, and S/2005 P2
Stern, S. Alan; Young, Leslie A.; Buie, Marc W. +2 more
We present new astrometry of Pluto's three satellites from images taken of the Pluto system during 2002-2003 with the High Resolution Camera mode of the Advanced Camera for Surveys instrument on the Hubble Space Telescope. The observations were designed to produce an albedo map of Pluto, but they also contain images of Charon and the two recently …
Discovery of Ultracompact Dwarf Galaxies in the Virgo Cluster
Drinkwater, M. J.; Jones, J. B.; Phillipps, S. +7 more
We have discovered nine ultracompact dwarf galaxies (UCDs) in the Virgo Cluster, extending samples of these objects outside the Fornax Cluster. Using the Two Degree Field (2dF) multifiber spectrograph on the Anglo-Australian Telescope, the new Virgo members were found among 1500 color-selected, starlike targets with 16.0<bj<20.2 i…
Detection of Six Trans-Neptunian Binaries with NICMOS: A High Fraction of Binaries in the Cold Classical Disk
Noll, Keith S.; Stephens, Denise C.
We have analyzed a homogeneous set of observations of 81 trans-Neptunian objects obtained with NIC2 on the Hubble Space Telescope with the goal of identifying partially resolved binaries. Using PSF fitting we have identified six likely binaries in addition to the three new binaries already found in this data set. We find that 11+5-…