Search Publications
EXOSAT Observations of 3C 371
Worrall, D. M.; Brunner, H.; Staubert, R.
The N galaxy/BL Lacertae object 3C 371 was observed by EXOSAT on two occasions separated by 18 days in September 1984. The low-energy and medium-energy X-ray flux has varied on the time scale of years (in comparison with HEAO 1 and Einstein Observatory measurements), 18 days (between the authors' two observations), and 8 hr to about 25 minutes wit…
Epsilon Aurigae: Polarization, Light Curves, and Geometry of the 1982--1984 Eclipse
Ake, T. B.; Simon, T.; Kemp, J. C. +5 more
Polarization and light curves of the recent eclipse of ɛ Aur are presented and modeled, using a tilted, opaque secondary disk and a model atmosphere for the F Ia primary star. That model qualitatively explains the striking asymmetries in the observed curves. But out-of-eclipse polarimetry shows the primary to be a nonradial pulsator, and this will…
Variability of Ultraviolet Emission in the Carbon Star TX PISCIUM
Johnson, Hollis R.; Baumert, John H.; Querci, Francois +1 more
Multiple low-resolution IUE observations of the cool carbon star TX Psc (NO; C6,2) permit an analysis of the variations in strength of the strongest emission lines - the Mg II line at 2800 Å, the C II line at 2330 Å, and certain Fe II lines. In the present sample of nine spectra, the integrated flux of the Mg II line varies by at least a factor of…
The Detection of Photospheric X-Ray Pulsations from PG 1159-035 with EXOSAT
Winget, D. E.; Barstow, M. A.; Holberg, J. B. +1 more
The detection of soft X-ray pulsations from the hot, helium-rich, degenerate object, PG 1159-035 is reported. These observations, obtained with the Low Energy experiment on EXOSAT, show the presence of large-amplitude soft X-ray (44-150 A) pulsations analogous to several of the low-amplitude, nonradial, g-mode pulsations which are observed in the …
Ultraviolet Spectrophotometry of Three LINERs
Keel, W. C.; Goodrich, R. W.
Three galaxies known to be LINERs were observed spectroscopically in the ultraviolet in an attempt to detect the presumed nonthermal continuum source thought to be the source of photoionization in the nuclei. NGC 4501 was found to be too faint for study with the IUE spectrographs, while NGC 5005 had an extended ultraviolet light profile. Compariso…
Ultraviolet Observations of V471 Tauri: Evidence for a Nova-like Outburst?
Bruhweiler, F. C.; Sion, E. M.
A search for accretion of wind-flare material onto the white dwarf in V471 Tauri has unexpected by revealed what appears to be shortward-shifted absorption, centered on two distinct velocities, near heliocentric velocities of -300 and -590 km/s in the line of sight toward V471 Tauri. The possibility that these features are due to instrumental effe…
The Strong UV Source in the Active E Galaxy NGC 4552
Thuan, T. X.; Puschell, J. J.; Oconnell, R. W.
1200-3200 A IUE spectra of the nucleus of NGC 4552 (M89) were obtained in order to investigate the nature of the strong 10 micron source in this Galaxy. There is a strong, extended UV source in NGC 4552 which has a spatial distribution nearly identical with that at optical wavelengths and is undoubedly stellar in origin. Its properties are consist…
Far-Ultraviolet Fluorescence of Carbon Monoxide in the Red Giant Arcturus. II. Analysis of High-Dispersion IUE Spectra
Ayres, T. R.
Faint, diffuse emissions near 1380 A in deeply exposed IUE spectrograms of the red giant Arcturus very likely are associated with bands of the A-X fourth-positive system of carbon monoxide, fluoresced by multiplet UV2 of neutral oxygen near 1305 A. Numerical simulations indicate that the strength of the CO bands is exceedingly sensitive, in the be…
X-ray spectrum of the 2A 0335+096 cluster of galaxies.
Singh, K. P.; Westergaard, N. J.; Schnopper, H. W.
The paper presents the X-ray spectrum of a poor cluster of galaxies 2A 0335 + 096 obtained with the medium energy and the gas scintillation proportional counter experiments on board Exosat. The observed spectrum is best explained by a thermal bremsstrahlung emission process from a hot intracluster gas with a temperature of about 3.4 x 10 to the 7t…
The Cepheid Mass Problem and Cepheid Binaries
Bohm-Vitense, E.
Existing mass determinations for Cepheids with different periods are examined. Wesselink masses are independent of the adopted distance scale. For short periods (less than 6 days) they follow the sequence of evolutionary masses. For periods longer than 10 days they are lower by up to a factor of 2. The lower mass branch joins up with the bump mass…