Search Publications
Rapid Line Variations in the Far-Ultraviolet Spectrum of 21 Com. I. The 1979 Event
Monier, R.
An analysis of archival IUE spectra of 21 Com revealed an instance of large and rapid flux variations on a time scale of 1 hr which occurred on November 15, 1979. Deep and broad features developed in less than 60 min and vanished in about 45 min shortwards of 1720 A. The 1979 event is thought to reflect a transient and abrupt change in the outer l…
HD 43246 and HD 127208: Two Unusual F-G + B Binary Systems
Parsons, Sidney B.; Fekel, Francis C.; Dempsey, Robert C. +1 more
New optical spectroscopic observations along with ultraviolet IUE observations have been obtained for the two interacting F or G III + B V binaries: HD 43246 and HD 127208. Photometric observations indicate random changes superimposed on regular ellipsoidal light variations, the latter probably the result of tidal distortion of the giant primaries…
EXOSAT Observations of the Blazar PKS 1510-089
Singh, K. P.; Rao, A. R.; Vahia, M. N.
A detailed study of X-ray emission from the high-polarization quasar PKS 1510-089, also known as a blazar, is presented, based on the EXOSAT observations in 1984 and 1985. The data were obtained from the EXOSAT archives. There is no evidence for any variations in the X-ray intensity on hourly time scales during either of the two observations. The …
X-ray observations of the radio galaxy Pictor A.
Singh, K. P.; Rao, A. R.; Vahia, M. N.
strong X-ray emission is detected from the active nucleus of an emission- line radio galaxy Pictor A, during observations with the EXOSAT observatory. The nuclear X-ray emission is observed to be steady on time- scales of a few minutes to a few hours. The X-ray spectrum is adequately explained by a simple power law with the photon index {GAMMA} = …
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.