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X-ray observations of Vela-X
Smith, A.; Zimmermann, H. U.
Exosat ME observations of the Vela-X region are presented. It is found that the 2-10 keV emission is divided into two components. One is associated with the rulsar but is probably extended by 10-20 arc minutes, the other is associated with the Vela-X radio nebula and is probably more extended (≈ 1 degree). The Vela-X component is softer than the p…
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…
Cos-B Gamma-Ray Sources and Interstellar Gas
Caraveo, P. A.; Bignami, G. F.; Strong, A. W. +8 more
Of the gamma-radiation observed above 100 MeV only a few percent is due to the catalogued sources which are viewed against intense background mission from the Galactic plane. There has been considerable recent success in modelling the Galactic plane emission as the interactions of cosmic rays with atomic and molecular interstellar gas; Bloemen, et…
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.
IUE observations of the RS CVn systems Z Her, TY Pyx and HD 155555.
Fernandez-Figueroa, M. J.; de Castro, E.; Gimenez, A.
Short wavelength (λλ1150 - 1950 Å) low resolution ultraviolet spectra of three RS CVn regular-period binary systems, obtained with the IUE satellite, have been examined. Newly observed spectra were compared with those retrieved from the IUE data bank. The surface fluxes of chromospheric and transition region lines were obtained and are briefly dis…
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.…
EXOSAT Observations of Late-Type Stars - the Application of Coronal Loop Models
Monsignori-Fossi, B. C.; Landini, M.; Pallavicini, R.
We apply solar-type coronal loop models to X-ray and UV observations of late-type stars. We derive from EXOSAT and IUE observations constraints on the temperature, pressure and size of the emitting structures.
Thermal radiation from a radio pulsar PSR 1055-52
Aschenbach, B.; Brinkmann, W.; Oegelman, H.
The radio pulsar PSR 1055 - 52 was studied in order to detect thermal radiation from the surface of a neutron star. Einstein satellite observations of PSR 1055 - 52 fitted to different spectra are described. These results and observations of an extended source around PSR 1055 - 52 were used by Cheng and Helfand (1983) to develop the theory of a sy…