Optical photometry of massive X-ray binaries : CEN X-3/V779 Cen.
Abstract
The results of photometric observations of V779 Cen, the optical counterpart of the massive X-ray binary Cen X-3, are presented. By combining these results with previously published data, an average light curve is derived. This curve shows the customary double-wave shape, with equal maxima and unequal minima, characteristic of ellipsoidal variations of a tidally distorted, gravitationally darkened, primary star. The light curve is shifted, by about 0.015 cycles, with respect to the X-ray ephemeris. Only by stretching the system parameters to their extreme limits can the amplitudes of the light curve be understood as a result of ellipsoidal variations only, and an additional source of light is probably present in this system. Since Cen X-3 is likely to be powered by Roche-lobe overflow, it is attractive to identify this light source, which contributes about 2 percent to the optical brightness of Cen X-3, with an accretion disk. No convincing evidence is found for the presence of long-term periodic variations in the shape of the light curve, with amplitudes in excess of about 0.01 mag.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 1983
- Bibcode:
- 1983A&A...124..294V
- Keywords:
-
- Binary Stars;
- Centaurus Constellation;
- Light Curve;
- Stellar Spectrophotometry;
- Variable Stars;
- X Ray Binaries;
- X Ray Sources;
- Accretion Disks;
- Neutron Stars;
- Orbital Elements;
- Stellar Magnitude;
- Ubv Spectra;
- Astrophysics