Search Publications
Another Search for Maia Variable Stars
Percy, John R.; Wilson, Joseph B.
We have used the Hipparcos epoch photometry database, and autocorrelation analysis, to search for the elusive Maia variables-short-period B7-A3 near-main-sequence pulsating variable stars. Of several hundred stars considered, and several dozen stars studied in detail, only a handful are possible variables: three are possible shallow eclipsing vari…
On Deriving Distances from Cepheids Using the Hubble Space Telescope
Saha, A.; Labhardt, Lukas; Prosser, Charles
In this paper we examine the methodology of obtaining Cepheid-based distances to galaxies from image data obtained with the Wide Field Planetary Camera (WFPC2) on the Hubble Space Telescope. We identify the sources of error and how these propagate to the derived distances for the particular method utilizing the modified DoPHOT program for photomet…
C32: A Young Star Cluster in IC 1613
Hodge, Paul W.; Wyder, Ted K.; Cole, Andrew
The Local Group irregular galaxy IC 1613 has remained an enigma for many years because of its apparent lack of star clusters. We report the successful search for clusters among several of the candidate objects identified many years ago on photographic plates. We have used a single Hubble Space Telescope WFPC2 pointing and a series of images obtain…
The Surface Temperatures of White Dwarf Accretors in Dwarf Novae: The Active Dwarf Nova CN Orionis during Quiescence
Mittal, R.; Urban, J.; Lyons, K. +3 more
We have carried out a synthetic spectral analysis of five IUE NEWSIPS archival spectra of the peculiar, very active dwarf nova CN Orionis taken at the system's lowest flux levels during quiescence. AAVSO data indicate the visual magnitude V~14 for CN Ori at this time. On the assumption that the white dwarf contributes significantly to the far-UV l…
Systematic Differences between the FK5 Proper-Motion System and Hipparcos
Zhu, Zi
We present an intensive analysis of the FK5 proper-motion system via the two large astrographic catalogs, the PPM and ACRS catalogs, compared with the Hipparcos proper motions. Region-, magnitude-, and color-dependent systematic errors in the PPM and ACRS proper motions are found and exhibit similar tendencies for both catalogs. The term of the gl…
Hubble Space Telescope Observations of M Subdwarfs
Gizis, John E.; Reid, I. Neill
We present the results of a Hubble Space Telescope snapshot program to search for very low mass stellar companions to nearby M subdwarfs. None of our nine targetted metal-poor primaries has companions more massive than the hydrogen burning limit, implying that the halo binary fraction is equal to or less than the Galactic disk binary fraction belo…
A Search for Exozodiacal Dust and Faint Companions near Sirius, Procyon, and Altair with the NICMOS Coronagraph
Brown, Michael E.; Kuchner, Marc J.
We observed Sirius, Altair, and Procyon with the NICMOS coronagraph on the Hubble Space Telescope to look for scattered light from exozodiacal dust and faint companions within 10 AU from these stars. We did not achieve enough dynamic range to surpass the upper limits set by IRAS on the amount of exozodiacal dust in these systems, but we did set st…
EC 11481-2303: A Peculiar Hot High-Gravity Pre-White Dwarf
O'Donoghue, Darragh; Sion, E. M.; Holberg, J. B. +6 more
We report the discovery of a peculiar new hot high-gravity predegenerate star, EC 11481-2303 from the Edinburgh-Cape Blue Object Survey, based upon the analysis of far-UV International Ultraviolet Explorer (IUE) echelle and low-resolution spectra and an optical spectrum. The IUE spectra reveal the presence of far-UV photospheric/circumstellar high…
The Ultraviolet Spectrum of VV Cephei Out of Eclipse
Bennett, Philip D.; Bauer, Wendy Hagen
The International Ultraviolet Explorer (IUE) satellite observed VV Cephei (M2 Iab+B?) over nearly a full 20.3 year orbital period, but all the observations were obtained outside total eclipse. Egress of the chromospheric eclipse was the only portion of the eclipse observed by IUE. We have examined all 124 high-resolution IUE spectra of VV Cephei a…
CaII K Emission-Line Asymmetry among Red Giants Detected by the ROSAT Satellite
Smith, Graeme H.; Shetrone, Matthew D.
Spectra of the Ca II H and K lines are reported for a number of field giants from which soft X-ray emission was detected by the ROSAT satellite. Several of these stars are RS CVn systems and exhibit very strong Ca II emission. The majority of the noninteracting giants in the sample have MV>-2.0, as determined from Hipparcos parallaxe…