The nature of X-ray binaries III. Evolution of massive close binaries with one collapsed component - with a possible application to Cygnus X-3.
Abstract
Summary. The evolution is computed for close binaries consisting of a massive primary (15 M0 or 21 M0) together with a neutron star secondary (M0 or 2 M0) with orbital periods between 2 and 6 days. Two cases are considered, viz. (i) the neutron star is able to accrete the 10- M0/yr lost by the primary after this star has started to overflow its Roche lobe, and (ii) accretion onto the neutron star is limited to l0- M0/yr, due to the critical luminosity; in case (ii) practically all mass lost from the primary is lost from the system or is dispersed around the system. In all cases it is found that before the system stabilizes the primary looses most of its hydrogen-rich outer layers and becomes a hot luminous star, mainly consisting of helium. In case (i) the secondary becomes a massive black hole and the final binary period is of the order of a few hours. Also in case (ii) the binary period decreases drastically even if the escaping matter carries with it a minor fraction (< 10 %) of the dynamical energy of the system. It is suggested that the final systems may be identified with X-ray sources such as Cygnus X-3 (Px = 4h8) In case of a black hole (instead of a neutron star) secondary the evolution of the system is expected to follow a similar pattern. Key words: evolution - close binaries - X-ray sources - collapsed stars
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 1973
- Bibcode:
- 1973A&A....25..387V