Ionization Structure of Cygnus X-3: A Massive Iron-depleted Companion?
Abstract
The ionization structure of Cygnus X-3 is studied. The ionization equilibrium of a dense stellar wind exposed to the strong X-ray radiation from the compact object is solved, and the emergent X-ray spectrum is compared with spectral observations with Ginga satellite to derive constraints on the mass of a companion star and the composition of stellar wind. We find that the iron edge energy favors a massive companion (5 approximately 10 solar mass), and the unionized iron column density suggests an iron-depleted gas component (10% approximately 50% of the cosmic abundance). Phase-to-phase variations in X-ray spectra, furthermore, due to the orbital motion, are reproduced if either carbon, nitrogen, or oxygen is 10-100 times more abundant than the cosmic abundance. These results are completely consistent with the recent observational results in the infrared, suggesting that the companion of Cygnus X-3 is a Wolf-Rayet star, especially a nitrogen-rich WN star.
- Publication:
-
The Astrophysical Journal Supplement Series
- Pub Date:
- June 1994
- DOI:
- 10.1086/192000
- Bibcode:
- 1994ApJS...92..477T
- Keywords:
-
- Companion Stars;
- Stellar Composition;
- Wolf-Rayet Stars;
- X Ray Astronomy;
- X Ray Binaries;
- X Ray Spectra;
- Ginga Satellite;
- Iron;
- Stellar Models;
- Stellar Winds;
- Astronomy;
- STARS: BINARIES: CLOSE;
- STARS: INDIVIDUAL CONSTELLATION NAME: CYGNUS X-3;
- STARS: WOLF-RAYET;
- X-RAYS: STARS