Search Publications
The Structure and Stellar Content of the Central Region of M33
Frogel, Jay A.; Stephens, Andrew W.
Using Gemini QuickStart infrared observations of the central 22" of M33, we analyze the stellar populations in this controversial region. Based on the slope of the giant branch we estimate the mean metallicity to be -0.26+/-0.27, and from the luminosities of the most luminous stars, we estimate that there were two bursts of star formation, ~2 and …
Detection of Two Binary Trans-Neptunian Objects, 1997 CQ29 and 2000 CF105, with the Hubble Space Telescope
Buie, Marc W.; Noll, Keith S.; Stephens, Denise C. +6 more
Images of the trans-Neptunian objects 1997 CQ29 and 2000 CF105 obtained with the Hubble Space Telescope WFPC2 camera show them to be binary. The two components of 1997 CQ29 were separated in our images by 0.20"+/-0.03" in 2001 November and by 0.33"+/-0.01" in 2002 June/July. The corresponding minimum physical dista…
HUBBLE SPACE TELESCOPE Survey of Clusters in Nearby Galaxies. I. Detection and Photometry
Dolphin, Andrew E.; Kennicutt, Robert C., Jr.
We have developed photometric techniques that can be applied to images with highly variable backgrounds, as well as to slightly extended objects (object size comparable to or smaller than point-spread function [PSF] size). We have shown that ordinary stellar PSF-fitting photometry can be applied to slightly extended objects provided that one appli…
The Ultraviolet Spectrum of the Ultracompact X-Ray Binary 4U 1626-67
Anderson, Scott F.; Wachter, Stefanie; Margon, Bruce +1 more
We have obtained Hubble Space Telescope/Space Telescope Imaging Spectrograph low-resolution ultraviolet spectra of the X-ray pulsar 4U 1626-67 (=KZ TrA); 4U 1626-67 is unusual even among X-ray pulsars because of its ultrashort binary period (P=41.4 minutes) and remarkably low mass function (<=1.3×10-6 Msolar). The far-UV s…
Hubble Space Telescope NICMOS Observations of Classical Nova Shells
Gehrz, Robert D.; Krautter, Joachim; Woodward, Charles E. +8 more
We present results of a campaign to obtain near-infrared images of evolved classical nova shells by using the Near-Infrared Camera and Multi-Image Spectrometer (NICMOS) on the Hubble Space Telescope. Images were obtained in six filters from 1.87 to 2.37 µm. Three of our four targets, QV Vulpeculae (Nova Vul 1987), QU Vulpeculae (Nova Vul 198…
Multiwavelength Study of the Nebula Associated with the Galactic LBV Candidate HD 168625
Nota, A.; Smith, L. J.; Clampin, M. +3 more
We present high-resolution HST imaging of the nebula associated with the Galactic luminous blue variable candidate HD 168625, together with ISO imaging and Anglo-Australian Telescope echelle spectroscopy. The overall nebular morphology is elliptical, with the major axis at P.A.~=120°. The dimensions of the nebula are 12"×16.7" at Hα and 15.5"×23.5…
A Critical Examination of Hypernova Remnant Candidates in M101. II. NGC 5471B
Lai, Shih-Ping; Chu, You-Hua; Wang, Q. Daniel +2 more
NGC 5471B has been suggested to contain a hypernova because of its extraordinarily bright X-ray emission. To assess its true nature, we have obtained high-resolution images in continuum bands and nebular lines with the Hubble Space Telescope, and high-dispersion long-slit spectra with the Kitt Peak National Observatory 4 m echelle spectrograph. Th…
Color Gradients and Surface Brightness Profiles of Galaxies in the Hubble Deep Field-North
Moth, Pimol; Elston, Richard J.
We fit elliptical isophotes to the Hubble Deep Field North WFPC-2 and NICMOS data to study the rest-frame (UV218-U300)0 color profiles and rest-frame B surface brightness profiles of 33 intermediate-redshift galaxies (0.5<=z<=1.2) with I814<25 and 50 high-redshift galaxies (2.0<=z<=3.5) wi…
On the Recent History of Star Formation in the Blue Compact Dwarf Galaxy VII Zw 403
Tenorio-Tagle, G.; Muñoz-Tuñón, C.; Silich, S. +1 more
Here we attempt to infer the recent history of star formation in the BCD galaxy VII Zw 403, based on an analysis that accounts for the dynamics of the remnant generated either by an instantaneous burst or by a continuous star formation event. The models are restricted by the size of the diffuse X-ray-emitting region, the Hα luminosity from the sta…
Assessing Formation Scenarios for the Double Nucleus of M31 Using Two-Dimensional Image Decomposition
Peng, Chien Y.
The double nucleus geometry of M31 is currently best explained by the eccentric disk hypothesis of Tremaine, but whether the eccentric disk resulted from the tidal disruption of an inbounding star cluster, from a nuclear black hole, or from an m=1 perturbation of a native nuclear disk remains debatable. I perform detailed two-dimensional decomposi…