X-Ray Variability in V444 Cygni: Evidence for Colliding Winds?
Abstract
Phase-resolved ROSA T observations of the soft X-ray flux from the W-R + 0 star binary V444 Cyg confirm the orbital dependence of the flux suggested by Einstein IPC observations, showing a drop in flux around primary eclipse, when the W-R star is in front of the 0 star. The observed X-ray variability can be modeled as a wind eclipse of an X-ray source by the Wolf-Rayet wind. If most of the X-rays from the system are produced in a region of shock-heated gas formed by the wind collision between the two stars, then the shocked gas has a large physical extent (r ∼ l4ORWR) if the observed variability is produced solely by the eclipse of the region by the W-R wind. However, since the 0 star makes a significant contribution to the total X-ray flux from the system, the actual size of the shocked interaction region is probably much smaller. We discuss possible origins for the X-ray emission and conclude that it is probable that at least a fraction of the observed X-ray emission comes from the wind collision.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 1996
- DOI:
- 10.1086/177334
- Bibcode:
- 1996ApJ...464..434C
- Keywords:
-
- STARS: BINARIES: ECLIPSING;
- SHOCK WAVES;
- STARS: INDIVIDUAL CONSTELLATION NAME: V444 CYGNI;
- STARS: MASS LOSS;
- X-RAYS: STARS