Search Publications
The Variable Iron Line in CYGNUS-X-3
van der Klis, M.; Manzo, G.; Smith, A. +3 more
Cygnus X-3 was observed with the GSPC on board EXOSAT on several occasions, one observation lasting for 7 orbital cycles. The width W and centroid energy E of the iron emission feature near 6.7 keV show a smooth, correlated, sinusoidal-type modulation, the iron line being widest and E being lowest just before X-ray maximum. The line profile may sh…
Spectral variability of scorpius X-1, as observed with EXOSAT
Mewe, R.; Heise, J.; Brinkman, A. C. +3 more
EXOSAT measurements of Sco X-1 have been carried out with the 500 l/mm and 1000 l/mm grating spectrometers and simultaneously with the gas scintillation proportional counter (GSPC) on two occasions in August 1983. The first observing period, part of the instrument performance verification phase, on August 7 and 8, 1983, lasted for about twenty two…
EXOSAT Observations of M Dwarfs
Schmitt, J. H. M. M.; Sztajno, M.
We give a progress report of our EXOSAT observations of active M dwarfs. The possibilities of filter spectroscopy of coronal X-ray sources using the available CMA filters are discussed, and we confirm that M dwarfs are rather hot coronal sources with X-ray temperatures in excess of 107 K, a result previously obtained with the Einstein O…
An Investigation Into the Nature of the 4.4-HOUR Periodic Source 4U1755-33
Parmar, A. N.; White, N. E.; Mason, K. O. +1 more
We present the results of a continuous 18 hour observation of 4U1755-33 made with the European Space Agency's EXOSAT Observatory. Four 50 min dips in X-ray intensity were observed equally spaced with a period of 4.4 hrs, confirming the periodicity first suggested in White et al. (1984). The dips are spectrally independent. We examine the propertie…
Detection of Iron Lines in the Persistent Emission of Some X-Ray Burst Sources Observed by EXOSAT
Hasinger, G.; Sztajno, M.; Truemper, J. +1 more
We have observed the X-ray burst sources 4U1728-33 and 4U1813-14 with the ME detectors aboard EXOSAT, and present here results of a spectral analysis of their persistent emissions. For both sources the data can be well fitted by a double blackbody continuum and a Gaussian emission line. The two spectral components can be interpreted in terms of a …
An EXOSAT observation of the peculiar X-ray binary 2S 0921-630 during optical eclipse
Branduardi-Raymont, G.; Mason, K. O.; Cordova, F. A. +1 more
An x-ray observation of 2S 0921-630 has been made coincident with the time of optical eclipse of this 9-day binary. No significant reduction in X-ray flux is measured. This can be explained if the binary orbit is viewed almost exactly edge-on, so that the central X-ray emitting star is obscured by the accretion disk from direct view. The X-rays th…
Cygnus X-3 not Seen at High-Energy Gamma-Rays
Hermsen, W.
The ESA satellite COS-B viewed the Cyg-X region 7 times between November 1975 and March 1982. A search for periodic gamma-ray emission (E > 70 MeV) from Cyg X-3 at the characteristic ∼4.8 h period did not reveal the source. Combining all observations, the 2σ upperlimit (E > 70 MeV) on the flux for the phase interval in which X-ray emission h…
X-Ray Observations of Active Chromosphere Stars
Bedford, D. K.; Eyles, C. J.; Elliott, K. H.
HD3196 = 13 Cet α, HD30495 = 58 Eri and HD32918 have been detected as new late-type soft X-ray sources. HD32918 is a member of the FK Com class.
X-Ray Variability of the Bright Bl-Lacertae Object PKS2155-304
Maccagni, D.; Maraschi, L.; Tanzi, E. G. +3 more
We have observed the BL Lac object PKS 2155-304 with the EXOSAT observatory and with IUE on 1983 October 31 and November 29. At the same time, optical photometry has been obtained. Variability has been observed both on a time scale of hours during the October 31 observation and on the time scale of one month. During the November 29 observation the…
The soft X-ray spectrum of NGC 4151
Culhane, J. L.; Warwick, R. S.; Pounds, K. A. +1 more
EXOSAT observations of the Seyfert galaxy NGC 4151 over the period July 1983 to April 1984 have revealed a decreasing flux in the 2 10 keV band. In accord with previous measurements a power law spectrum attenuated with a simple column of cold gas does not provide a satisfactory spectral fit below ∼3 keV, where a lower relative opacity is required.…