Search Publications
High Resolution Imaging of Galaxy Cores
Boksenberg, A.; Barbieri, C.; Weigelt, G. +17 more
Surface photometry data obtained with the Faint Object Camera of the Hubble Space Telescope in the cores of ten galaxies is presented. The major results are: (i) none of the galaxies show truly "isothermal" cores, (ii) galaxies with nuclear activity show very similar light profiles, (iii) all objects show central mass densities > 10^3^M_sun_ pc…
Stellar Kinematic Groups. I. The URSA Major Group
Soderblom, David R.; Mayor, Michel
The Ursa Major Group (UMaG) is studied as a test case for the authenticity of Stellar Kinematic Groups, using Coravel radial velocities, recent compilations of astrometric data, and new spectroscopic observations. Spectroscopic age indicators, particularly indices of the strength of chromospheric emission, are applied to solar-type candidate membe…
Evolution of the Symbiotic Binary System AG Pegasi: The Slowest Classical Nova Ever Recorded
Polidan, Ronald S.; Mikolajewska, Joanna; Slovak, Mark H. +2 more
We present an analysis of new and existing photometric and spectroscopic observations of the ongoing eruption in the symbiotic star AG Pegasi, showing that this binary has evolved considerably since the turn of the century. Recent dramatic changes in both the UV continuum and the wind from the hot component allow a more detailed analysis than in p…
Wide Field Camera Observations of Baade's Window
Faber, S. M.; Holtzman, Jon A.; O'Neil, Earl J., Jr. +7 more
We have observed a field in Baade's Window using the Wide Field Camera (WFC) of the Hubble Space Telescope (HST) and obtain V- and I-band photometry down to V approximately 22.5. These data go several magnitudes fainter than previously obtained from the ground. The location of the break in the luminosity function suggests that there are a signific…
The Early Ultraviolet Spectral Evolution of Nova Cygni 1992
Ake, T. B.; Shore, Steven N.; Sonneborn, George +2 more
We report on the high resolution ultraviolet line profile evolution of Nova Cygni 1992 using the International Ultraviolet Explorer (IUE) satellite and the Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope (HST). Our observations cover the period from discovery in 1992 February through 1993 April. The initial expansion velo…
A Hubble Space Telescope Planetary Camera View of Giant H II Regions: The Wolf-Rayet Content of NGC 595 and NGC 604 in M33
Drissen, Laurent; Moffat, Anthony F. J.; Shara, Michael M.
We present images of NGC 595 and NGC 604, the most massive giant H II regions in M33, obtained with the Planetary Camera aboard the Hubble Space Telescope in order to study their Wolf-Rayet (WR) population. Fourteen WR and/or Of candidates are detected in NGC 604, and eleven in NGC 595. All previously claimed "superluminous" WR stars are found to …
Gravitational Lensing Statistics Based on a Large Sample of Highly Luminous Quasars
Magain, P.; Filippenko, A. V.; Surdej, J. +6 more
Results on gravitational lensing statistics applied to a sample of 469 highly luminous quasars are reported. The objects were directly imaged, either from the ground (ESO, CFH) under optimal seeing conditions, or using the Hubble Space Telescope. We have derived values for the effectiveness parameter F of galaxies, modeled by means of singular iso…
Binary Star Orbits From Speckle Interferometry. V. A Combined Speckle/Spectroscopic Study of the O Star Binary 15 Monocertis
Gies, Douglas R.; Shara, Michael M.; Penny, Laura R. +7 more
We report on the discovery of a speckle binary companion to the O7 V (f) star 15 Monocerotis. A study of published radial velocities in conjunction with new measurements from Kitt Peak National Observatory (KPNO) and IUE suggests that the star is also a spectroscopic binary with a period of 25 years and a large eccentricity. Thus, 15 Mon is the fi…
PG 0308+096 and PG 1026+002: Two New Short Period Binary Stars Resulting From Common-Envelope Evolution
Green, Richard F.; Sion, Edward M.; Saffer, Rex A. +5 more
Ultraviolet spectroscopy, optical spectroscopy, and spectrophotometry have been used to study the excess UV stars PG 0308 + 096 and PG 1026 + 002. Both objects are short-period binary systems, each containing a DA white dwarf star and a dM star. Orbital periods of approximately 0.284 day for PG 0308 + 096, and aproximately 0.597 day for PG 1026, h…
Hubble Space Telescope / Faint Object Camera Observations of the Inner Regions of the Galactic Globular Cluster M15
Paresce, F.; Ferraro, F. R.
A set of high resolution images of the core of the Galactic Globular Cluster M15 (NGC 7078) were obtained for the first time with the Faint Object Camera on the HST through the f/48-F140W, f/48-F220W and f/96-F342W ultraviolet filters. Two UV-Color-Magnitude Diagrams are presented for the approximately 300 objects measured in the 22 arcsec x 22 ar…