Search Publications
Ultraviolet Signposts of Resonant Dynamics in the Starburst-ringed SAB Galaxy M94 (NGC 4736)
Madore, Barry F.; Keel, William C.; O'Connell, Robert W. +10 more
The dynamic orchestration of star-birth activity in the starburst-ringed galaxy M94 (NGC 4736) is investigated using images from the Ultraviolet Imaging Telescope (UIT; far-ultraviolet [FUV] band), Hubble Space Telescope (HST; near-ultraviolet [NUV] band), Kitt Peak 0.9 m telescope (Hα, R, and I bands), and Palomar 5 m telescope (B band), along wi…
The Continuing Slow Decline of AG Pegasi
Kenyon, Scott J.; Proga, Daniel; Keyes, Charles D.
We analyze optical and ultraviolet observations of the symbiotic binary AG Pegasi acquired during 1992-1997. The bolometric luminosity of the hot component declined by a factor of 2-3 from 1980-1985 to 1997. Since 1992, the effective temperature of the hot component may have declined by 10%-20%, but this decline is comparable to the measurement er…
Abundances in the Planetary Nebula IC 5217
Feibelman, Walter A.; Hyung, Siek; Aller, Lawrence H. +1 more
High-resolution optical wavelength spectroscopic data were secured in the optical wavelengths, 3700-10050 Å, for the planetary nebula IC 5217 with the Hamilton Echelle Spectrograph at Lick Observatory. These optical spectra have been analyzed along with the near-UV and UV archive data. Diagnostic analyses indicate a nebular physical condition with…
The New Two-Image Gravitational Lens System CLASS B2319+051
Pearson, T. J.; Blandford, R. D.; Koopmans, L. V. E. +10 more
We report the discovery of a new two-image gravitational lens system, CLASS B2319+051, from the Cosmic Lens All-Sky Survey. Radio imaging with the Very Large Array (VLA) and Multielement Radio-linked Interferometer Network (MERLIN) shows two compact components with a flux density ratio of ~=5:1, separated by 1.36". Observations with the Very Long …
The Evolution of Galaxy Morphology for Galaxies in the Canada-France Redshift Survey
van den Bergh, Sidney
The images of 229 galaxies in the Canada-France Redshift Survey have been classified on the DDO system. These observations were combined with previous classifications of galaxies with known redshifts in the Hubble Deep Field. The combined sample provides homogeneous morphological classifications for 425 galaxies of known redshift. The fraction of …
Hubble Space Telescope NICMOS Imaging of the Cores of M31 and M32
Rieke, Marcia J.; Corbin, Michael R.; O'Neil, Earl
We present 1.1, 1.6, and 2.2 µm images of the cores of the Local Group galaxies M31 and M32 obtained with the Near Infrared Camera and Multi-Object Spectrometer of the Hubble Space Telescope (HST). These images are also compared with optical images of the galaxies obtained with the HST Wide Field Planetary Camera 2 (WFPC2). In M31, the nucle…
An Ultraviolet Study of the Short-Period Binary OO Aquilae
Guinan, Edward F.; Hrivnak, Bruce J.; Ribas, Ignasi +1 more
OO Aql is a rare W UMa-type eclipsing binary in which the two solar-type stars may have only recently evolved into contact. The binary has an unusually high mass ratio (0.84) and a relatively long orbital period (0.506 days) for its spectral type (mid-G). Twelve ultraviolet spectra of OO Aql were obtained in 1988 with the International Ultraviolet…
The Gravitational Lens Candidate FBQ 1633+3134
White, Richard L.; Gregg, Michael D.; Morgan, Nicholas D. +2 more
We present our ground-based optical imaging, spectral analysis, and high-resolution radio mapping of the gravitational lens candidate FBQ 1633+3134. This z=1.52, B=17.7 quasar appears double on CCD images with an image separation of 0.66" and a relatively constant flux ratio of ~3:1 across B, V, R, and I filters. A single 0.27 mJy radio source is …
Young Clusters in the Magellanic Clouds. II.
Da Costa, G. S.; Bessell, M. S.; Keller, Stefan C.
We present the results of a quantitative study of the degree of extension to the boundary of the classical convective core within intermediate-mass stars. The basis of our empirical study is the stellar population of four young populous clusters in the Magellanic Clouds that has recently been detailed by Keller, Bessell, & Da Costa. The sample…
Infrared Space Observatory Short Wavelength Spectrometer Observations of V1425 Aquilae (Nova Aquila 1995)
Morisset, C.; Humphreys, R. M.; Gehrz, R. D. +19 more
We present observations of the classical nova V1425 Aquilae (Nova Aquila 1995) with the Infrared Space Observatory's (ISO) Short Wavelength Spectrometer, the Isaac Newton Telescope's Intermediate Dispersion Spectrograph, and the International Ultraviolet Explorer's Short-Wavelength Primary Spectrograph. Analysis of He II (1640 Å) development const…