EXOSAT observations of Cygnus X-1: Study of the soft X ray excess
Abstract
Ten observations of Cygnus X-1 made by the EXOSAT medium energy experiment, in the period of 1984 to 1985 when the source was in its low state, are examined. The presence of a soft component (black body temperature of around 0.2 keV), on top of high energy power law component, is confirmed in all spectra. The emission line at 6.2 keV is also visible and its intensity varies during the dips. The soft component undergoes more distinct fluctuations than the hard one, which is well seen on a color-color and a color-intensity diagram. The results are discussed in the framework of an accretion disc model.
- Publication:
-
Contributions of the X Ray Astronomy Group of the Max-Planck-Institut fuer Extraterrestrische Physik
- Pub Date:
- November 1989
- Bibcode:
- 1989xras.rept...11B
- Keywords:
-
- Binary Stars;
- Black Holes (Astronomy);
- Exosat Satellite;
- X Ray Stars;
- Cygnus Constellation;
- European Space Programs;
- Satellite Imagery;
- Spectrum Analysis;
- X Ray Spectra;
- Astronomy