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An X-ray flare on the short-period, eclipsing binary UMa.
Jeffries, R. D.; Bedford, D. K.
An EXOSAT observation of a flare on the short-period, eclipsing RS CVn binary system XY UMa is reported. The light curve is interpreted within the framework of cooling plasma within loop-like magnetic structures, and limits on the flaring plasma and magnetic field parameters are derived using the light curve decay time and flare emission measure. …
Orbital Variability in the Wind of the Massive X-Ray Binary HD 153919/4U 1700-37
Hammerschlag-Hensberge, G.; Howarth, Ian D.; Kallman, Timothy R.
A set of forty high-dispersion IUE spectra of HD 153919, the Of-type primary in the 4U 1700-37 X-ray binary system, have been examined for evidence of orbital profile variability associated with the Hatchett-McCray effect. Although the effect is negligible in the resonance lines of C IV, Si IV, and N V, some subordinate lines show clear orbital ch…
A Search for Evidence of Past and Ongoing Mass Loss in the Hot DO Degenerates PG 1159-035, PG 1034+001, and KPD 0005+5106
Sion, Edward M.; Fritz, Matthew L.; Leckenby, Henry J.
The results are reported of a search for evidence of mass loss from three very hot, helium-rich degenerate stars, PG 1034 + 001, PG 1159 - 035, and KPD 0005 + 5106, based upon a search for weak, velocity-displaced line features in high-resolution IUE spectra. The search was entirely negative for PG 1159 - 035 and resulted in the detection of Si IV…
IUE and Optical Data during the Low State of H0538+608 (BY Camelopardalis)
Szkody, Paula; Mateo, Mario; Downes, Ronald A.
IUE short- and long-wavelength spectra, CCD differential BR photometry, and a portion of a J light curve were obtained during January-March 1989 when H0538 + 608 (BY Cam) was in a low state about 3 magnitudes below its normal high-state V magnitude. The IUE short-wavelength spectrum showed that all the strong emission lines apparent at the high st…
Search for Millisecond X-Ray Pulsations from the Galactic Bulge X-Ray Source GX 9+1
Michelson, P. F.; Norris, J. P.; Wood, K. S. +2 more
The recent discoveries of millisecond radio-pulsars with small period derivatives and quasi-periodic oscillations in bright Galactic X-ray sources have given rise to theories which predict that low-mass X-ray binaries should have low-amplitude X-ray pulsations with short, possibly millisecond, periods. Most previous searches for these pulsations s…
Cometary ion flow variations at comet P/Halley as observed by the Giotto IMS experiments.
Schwenn, R.; Balsiger, H.; Ip, W. -H. +5 more
Using the combined data sets from the angle analyzer and the mass analyzer of the Giotto IMS-HIS experiment, the authors have derived the three-dimensional plasma flow properties of cometary ions for masses ≥12 AMU. The results are in agreement with the theoretical model of charge exchange loss of the hot cometary ions.
The Ly-alpha and C IV lines in 10 low-redshift active galactic nuclei/quasars.
Buson, L. M.; Ulrich, M. -H.
We analyze the properties of the Ly α and C IV lines in 10 active galaxy nuclei/quasars with z < 0.2, for which relatively high quality spectra can be found in the first installment of the IUE "Uniform Low Dispersion Archives". A simple profile fitting of Ly α and of C IV with 2 gaussian components of different widths leads to the following res…
Ultraviolet Fluxes for Globular Clusters in M31: A Rediscussion
Crotts, Arlin P. S.; Cacciari, Carla; Kron, Richard G. +1 more
We discuss long-exposure observations of three bright globular clusters in M31 obtained with both the short- and long-wavelength low-resolution cameras of the International Ultraviolet Explorer satellite. All of the clusters are seen at the longer wavelengths, but only one of the clusters is seen at short wavelengths, and this detection is margina…
Simultaneous observations of the symbiotic star BF Cygni.
Gonzalez-Riestra, R.; Cassatella, A.; Fernandez-Castro, T. +1 more
Simultaneous ultraviolet/optical spectrophotometry and infrared photometry for the low excitation symbiotic star BF Cygni are presented. The analysis of the data suggests that three different components are present in the UV to IR energy distribution. A hot subdwarf with R = 0.48 solar radius and T not less than 60,000 K if the distance is 2.3 kpc…
Constraints on the inner accretion flow of 4U /MXB 1636-53 (V 801 Arae) from a comparison of X-ray burst and persistent emission.
van Paradijs, J.; Wijers, R. A. M. J.; Lewin, W. H. G. +4 more
A detailed analysis is presented of the importance of Comptonization in burst and persistent spectra of the low-mass X-ray binary 4U/MXB 1636-53, and from this analysis it is inferred that the inner accretion flow is geometrically thin. It is found that burst spectra of 1636-53 are very nearly Planckian in shape; from an upper limit to a high-ener…