Optical and X-ray observations of 4U2129+47/V1727 CYG in a quiescent state
Abstract
We observed the 5.2 h X-ray binary 4U2129+47 for more than one orbital cycle on 29 September and 4 October 1983 using the LE, ME and GSPC detectors of the ESA X-ray satellite EXOSAT. In neither detector an X-ray flux from the source could be detected. Quasi-simultaneous UBV observations using the 2.2 m telescop at the German-Spanish Astronomical Center, Calar Alto, failed to detect the large amplitude light curve reported in earlier observations but show the optical companion in a low intensity state. The large amplitude light curve has been interpreted as due to X-ray heating of the optical star by the X-ray source similar to the system Her X-1/HZ Her. Our optical observations indicate that the heating X-ray source has been shut off and nicely explain that EXOSAT failed to detect the source. 4U2129+47 seems to behave similar to Her X-1 in the optical quiescent state, seen for instance from 1949 to 1956.
- Publication:
-
Advances in Space Research
- Pub Date:
- 1985
- DOI:
- 10.1016/0273-1177(85)90462-4
- Bibcode:
- 1985AdSpR...5c.117P
- Keywords:
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- Exosat Satellite;
- Light Curve;
- Ubv Spectra;
- X Ray Binaries;
- Accretion Disks;
- Electrophotometry;
- Astrophysics