Search Publications
EXOSAT observations of X-rays from classical novae during the outburst stage.
Beuermann, K.; Krautter, J.; Oegelman, H.
Soft X-ray light curves of the classical novae Nova Muscae 1983 and Nova Vulpeculae 1984 No. 1 and No. 2 from optical maximum to about 900 days after maximum were sampled with the Exosat satellite, and the implications of the results for models of nova outbursts are considered. The observations seem best explained by the constant bolometric lumino…
Systematics of the CHON and Other Light Element Particle Populations in Comet p/ Halley
Kissel, J.; Clark, B. C.; Mason, L. W.
Based on chemical signatures measured by the PIA experiment during the Giotto flyby of comet P/Halley, a number of particle classifications have been designated. In addition to silicate-like grains and particles of mixed (cosmic) composition, there appear to be several light-element rich populations including the CHON, (H,C), (H, C, O), and (H,C,N…
EXOSAT Observations of Double-peaked Bursts with Radius Expansion from 4U/MXB 1820-30
Haberl, F.; Stella, L.; White, N. E. +2 more
A detailed analysis is presented of seven X-ray bursts from the X-ray source 4U/MXB 1820-30 in the globular cluster NGC 6624. The bursts were double-peaked, and recurred at almost equal time intervals of 3.2 hr. The persistent flux varied by only 10 percent on time scales of 60 minutes. The ratio of the total persistent energy emitted before a bur…
The Exotic Helium Variable PG 1346+082
Winget, D. E.; Wesemael, F.; Liebert, James +5 more
The results of an extensive study of the blue object PG 1346 + 082, which is both a photometric and a spectroscopic variable, are presented. The system spans the B magnitude range 13.6-17.2, is brighter than m(pg) of about 14.0 roughly 74 percent of the time, and has a photometric quasi-period of four to five days. The rapid photometric flickering…
CAL 83: A Puzzling X-Ray Source in the Large Magellanic Cloud
Thompson, I. B.; Crampton, David; Hutchings, J. B. +3 more
Spectroscopic observations of the X-ray point source no. 83 in the Columbia Astrophysics Laboratory Einstein survey of the Large Magellanic Cloud have been accumulated over 4 yr. The optical spectrum shows no stellar absorption features, but only emission lines typical of an accretion disk. Radial velocity measurements reveal a small (K = 30 km/s)…
Optical and UV Spectroscopy of the Black Hole Binary Candidate LMC X-1
Thompson, I. B.; Bianchi, L.; Hutchings, J. B. +2 more
Both further optical spectroscopy of the binary star identified with LMC X-1, obtained between 1983 and 1985, and a series of IUE UV spectra taken during a 5 day interval in 1984 are presented. The optical data are used to refine the orbital period to 4.2288 days, and improved orbital parameters are derived. The velocity of the optical emission li…
Multiwavelength monitoring of the dwarf nova VW Hydri. I. Overview.
van Paradijs, J.; Heise, J.; Verbunt, F. +7 more
Observations from different wavelength regions are used to investigate outburst mechanisms in VW Hydri. Previous observational data on VW Hydri and the present theoretical understanding of dwarf novae are first reviewed. Observational data from the current data set on ordinary outbursts are found to be self-consistently interpreted both by assumin…
Periodic Photospheric and Chromospheric Modulation in Alpha Orionis (Betelgeuse)
Sonneborn, G.; Dupree, A. K.; Guinan, E. F. +3 more
The bright cool supergiant Alpha Orionis has been monitored spectroscopically and photometrically over the past three years (1984-1986) in the optical and the ultraviolet wavelength regions. A 420-day periodic modulation of the flux is observed in the optical and ultaviolet continua, and in the Mg II line emission cores. Periodic photospheric puls…
Morphology and Nuclear Spectroscopy of Markarian 231
Hutchings, J. B.; Neff, S. G.
Deep optical imaging of Mkn 231 reveals twin (tidal?) tails, a linear nuclear feature at green wavelengths, and a very blue region 4 arcsec south of the nucleus. Much of the central part of the galaxy is red, but there are complex areas of blue luminosity outside this, and a sharp edge to the luminosity at a distance of about 16 arcsec from the ce…
Chromospheric and Transition-Region Emission from Young Solar-Type Stars in Clusters, Kinematic Groups, and the Field
Soderblom, David R.; Clements, Sandra D.
We have examined the strength of chromospheric and transition-region emission in solar-type stars that have been suggested to be members of the Ursa Major Group and Hyades Group (originally selected on kinematic grounds), as well as stars in the Hyades Cluster and other young stars of the solar neighborhood. We find that indices of the Ca II (R'