An Upper Limit to the Mass of the Black Hole in V404 Cygni
Abstract
We have measured the H-band light curve of the black hole binary V404 Cyg (=GS 2023+338). When folded at the spectroscopic orbital period, 6A714 days, the light curve has two maxima and two minima per orbit and a peak-to-peak amplitude of ∼0.25 mag. This variation is produced primarily by ellipsoidal variations of the KO IV star in the system, but the light curve is distorted by other sources of variability as well. Because of the distortions and because of an unknown contribution to the infrared flux from the accretion disk around the black hole, analysis of the ellipsoidal variations yields only a lower limit to the orbital inclination of V404 Cyg and, thus, an upper limit to the mass of its black hole. Our analysis of the H-band light curve yields an upper limit of 12.5 Msun. We show that previously published K-band light curves of V404 Cyg were probably also contaminated by other sources of variability. Reanalysis of the K-band data gives results consistent with the H-band data.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1996
- DOI:
- 10.1086/176981
- Bibcode:
- 1996ApJ...460..437S
- Keywords:
-
- STARS: BINARIES: CLOSE;
- BLACK HOLE PHYSICS;
- STARS: INDIVIDUAL CONSTELLATION NAME: V404 CYGNI;
- X-RAYS: STARS