The X-ray Eclipse of the Black-Hole Binary CAL 87
Abstract
ROSAT-PSPC observations of CAL 87, a black-hole candidate in the LMC, have been obtained throughout its 10.6-hour orbital cycle. These data show an X-ray minimum which coincides in phase with the deep optical eclipse. However, the X-ray eclipse has a duration of about 0.2P, compared to the optical eclipse which extends over almost half the orbital cycle. The drop in X-ray intensity is about a factor of two at phase zero, indicating the X-ray emitting region is not totally eclipsed. The shape and duration of the X-ray eclipse are similar to those seen in binary systems having accretion disk coronae, such as X1822-371. Out of eclipse the X-ray emission from CAL 87 shows some short timescale variability, with no evidence for phase-related modulations.
- Publication:
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American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1992
- Bibcode:
- 1992AAS...181.2008S