Search Publications
EXOSAT / Optical Observations of the Am-Herculis Star H0139-68
Motch, C.; Beuermann, K.; Schwope, A. +1 more
We report preliminary results of X-ray and optical observations of the AM Her star HO139-68 during its low state at V ∼ 17 to 18. X-rays were detected only during ∼ 45 % of the orbital period when the system was optically bright and the radial velocity of the Balmer lines was positive. Our data show no evidence for accretion onto two active poles …
EXOSAT and EINSTEIN High Resolution Images of the Small Magellanic Cloud
McHardy, I. M.; Jones, L. R.; Pye, J. P. +1 more
In order to obtain optical identifications and further information about the X-ray emission of sources discovered in the EINSTEIN IPC survey of the Small Magellanic Cloud (SMC), we have used the EXOSAT CMA and EINSTEIN HRI at selected positions. These observations have so far resulted in several identifications (including 4 stellar objects with m<…
Variability of Bl-Lacertae Objects at X-Ray and Other Frequencies
Pollock, A. M. T.; Robson, E. I.; Brand, P. W. J. L. +1 more
EXOSAT observations reveal that daily X-ray variability appears to be a common property of high luminosity BL Lac objects. Results are reported for PKS0735+178, OM280(=1147+245), OQ530(=1418+546), OV-236 (=1921-293) and OJ287(=0851+202). In OJ287, for which we have the most extensive coverage, the amplitude of variability at X-ray frequencies appe…
EXOSAT Observations of the Bright X-Ray Source GX9+1
Hasinger, G.; Sztajno, M.; Truemper, J. +1 more
We present the results of the spectral and timing analysis of an observation of GX9+1/4U1758-205 performed with the Medium Energy Experiment aboard EXOSAT. During our observation the source flux varied irregularly in time scales from minutes to hours. No periodic emission in the period range from 16 msec to 2000 sec was found with an upper limit o…
First Detection of an X-Ray Burst and a One-Hour Intensity Dip in 4U1323-62
van Paradijs, J.; van der Klis, M.; Jansen, F. +1 more
We report the results of a 1.4 104s observation of the region of 4U 1323-62 with the EXOSAT ME. The source has a flux of 7 8 10-11 erg/cm2s (2 10 keV) and a power-law spectrum with 1.1 < α < 1.8. During our observation, the source showed a symmetric 60% dip in its X-ray flux of R~1 hr. The spectrum hardens du…
Galactic Supernova Remnants
Aschenbach, B.
A progress report is given on our current interpretation of the X-ray emission from supernova remnants. Previous results from earlier experiments, the Einstein Observatory in particular, are reviewed and supplemented by the most recent data from the Exosat mission for a selection of remnants (Puppis-A, Cas-A, SN 1006, RCW103, W49B). Major improvem…
Coordinated optical-EXOSAT-tenma observations of a burst from 2S1636-536
van Paradijs, J.; Pedersen, H.; Lewin, W. H. G. +6 more
During a coordinated observations of 2S1636-536 with EXOSAT, Tenma and the 1.4 metre Danish telescope at La Silla, a single burst was detected at all three observatories. The burst was bright with a peak flux of 6 × 10-8 ergs/cm 2 /s and rapid expansion of the blackbody radius. EXOSAT and Tenma agree closely in the values of…
The X-Ray and Optical Variability of the BLRG 3C390.3
Ward, M.; Barr, P.; Shafer, R.
We describe the optical emission line and continuum changes in 3C390.3. Also we present new EXOSAT results, and discuss their implication for determination of the X-ray spectrum — spectral index and absorbing column.
X-Ray Variability of the Am-Herculis Star CW1103+254
Stella, L.; Beuermann, K.
The AM Her star CW1103+254 was observed with the low-energy and the medium-energy instruments of EXOSAT on 3 occasions for a total of 10.5 orbital cycles. Both, soft and hard X-rays from CW1103+254 were detected. We report preliminary results on the time variability of the X-ray emission on time scales from 1 minute to 1 month.
The Extremely X-Ray Bright Wolf-Rayet Star HD193793
Pollock, A. M. T.
The Einstein Observatory showed that Wolf-Rayet stars have a much larger range in the ratio of X-ray to bolometric luminosity than normal early-type stars. EXOSAT measurements of HD193T93 (WCT+abs) show it to be extremely X-ray bright. This result is probably not connected with the infra-red and radio outburst that the star underwent in 1977. Othe…