Search Publications
The Structure of Low-Mass X-Ray Binaries
White, N. E.; Mason, K. O.
The present knowledge of the structure of low-mass X-ray binary systems is reviewed. We examine the orbital period distribution of these sources and discuss how the orbital periods are measured. There is substantial observational evidence that the accretion disks in low-mass X-ray binaries are thick and structured. In a number of highly inclined s…
X-Ray Emission from Cataclysmic Variables
Mason, K. O.
EXOSAT results on cataclysmic variables are reviewed. The long continuous X-ray observations afforded by this observatory, coupled with the sensitivity of its instruments to medium energy and very low energy X-rays, have enabled the rotational and orbital X-ray light curves of these stars to be measured in unprecedented detail. Examples are given …
35-DAY Cycle and the Rotation Period of HERCULES-X-1
Pietsch, W.; Kahabka, P.; Truemper, J. +2 more
Sampling observations of a complete 35d cycle of Her X-1 during 1 March to 5 April 1984 with the low and medium energy X-ray detectors of EXOSAT are presented. The intensities measured in the Argon detectors are compared with the UHURU 35d light curve to obtain the turn-on times of two consecutive cycles as JD 2445753.0 ± 1.0…
New EXOSAT Results from the Intermediate Polar V1223-SAGITTARIUS
Beuermann, K.; Osborne, J. P.; Mason, K. O. +1 more
We report new results obtained from the EXOSAT AO- 1 observation of the intermediate polar V1223 Sgr. The detection of a 12.4 minute period in the medium energy X-ray flux with an associated hardness ratio variation has been previously reported in Osborne et al. (1984a). Further work has revealed: a narrow dip at the phase zero in the folded mediu…
Large Magellanic CLOUD-X-4 - 13.4 Pulsations and an X-Ray Flare Observed by EXOSAT
Pietsch, W.; Pakull, M.; Staubert, R. +1 more
EXOSAT observed LMC X-4 on November 17/19, 1983 for one 1.4 day binary period during the high state of the 30.5 day cycle. An eclipse with sharp ingress and slow egress was detected with an eclipse angle of 27.1±1.0 dgr. In the medium energy experiment the source showed a hard power law spectrum. Outside eclipse the source was remarkably constant …
2AO526-328 - the White Dwarf Rotation Period Revealed
van Paradijs, J.; van der Klis, M.; King, A. R. +4 more
We report results from EXOSAT observations of the intermediate polar system 2A0526-328 (TV Col). The hard X-ray emission (2 8 keV) is modulated with a period of 1943 s, interpreted as the white-dwarf rotation period. Soft and hard X-ray emission show intensity minima, in phase with the orbital period of 0.2286 days; analysis of the hard X-ray spec…
Magnetic Activity in Cool Stars
Schrijver, C. J.
Aspects of magnetic activity of late-type stars are reviewed: first, results obtained through the comparison of emissions from various temperature regimes in the outer atmospheres of cool stars, then results from stellar soft X-ray spectroscopy. Spectra obtained with different instruments (Imaging Proportional Counter and Solid State Spectrometer …
X-Ray Spectral Variability of 3C273
Molteni, D.; Staubert, R.; Turner, M. J. L. +2 more
3C273 has been monitored by EXOSAT over the period December 1983 to June 1984 in 4 observations. In the December observation the flux was high and the spectrum showed a power law index of 1.5 changing to 0.9 at∼8 keV. In subsequent observations the flux dropped to∼40% of its original value and the hard tail disappeared. In the last observation the…
Large Magellanic CLOUD-X-4 AO:538-66 and Surrounding X-Ray Sources Observed with EXOSAT
Pietsch, W.; Beuermann, K.; Pakull, M. +4 more
Repeated observations of LMC X-4 with EXOSAT were carried out in 1983/84 in order to study its 30.5 day cycle and to cover the expected outbursts of the recurrent LMC transient A0538-66. The latter source was inactive during our campaign although a variable circumstellar envelope was still present around the optical counterpart. At least ten furth…
Ss-Cygni in Outburst and Quiescence
Heise, J.; King, A. R.; Watson, M. G.
EXOSAT has been used to carry out a series of observations of the dwarf nova SS Cygni covering both quiescent and outburst states which provide a detailed picture of its behaviour at X-ray wavelengths. These results provide strong support for a new coronal model for the X-ray emission from non-magnetic white dwarf systems.