The evolution of low-mass close binary systems. I. The evolutionary fate of contact binaries

Journal Article · Mon Nov 01 04:00:00 EST 1976 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/154781· OSTI ID:7330133

Webbink, R F

A simple angular momentum argument shows that, if the absence of thermal equilibrium solutions for contact binary components prevents the growth of deep common envelopes, the mass ratio (secondary/primary) decreases on an evolutionary time scale until the secondary is completely dissipated, during the primary's initial ascent of the giant branch. If simultaenous thermal equilibrium for both components exists at some stage, the binary may overflow its outer critical surface, dissipating its orbital angular momentum in an ''excretion'' disk. Homogeneous evolution of the primary is observationally excluded.Gravitational radiation can significantly affect the evolution of a moderate- or low-mass system, but dominates only in the lowest-mass binaries. Considerations of thermal stability suggest that a contact system cannot survive as a binary beyond the main-sequence stage. Large-scale angular momentum loss as the primary attempts to cross the Hertzsprung gap renders the remnant indistinguishable from an ordinary single star. Angular momentum losses in a stellar wind during giant branch and asymptotic giant branch evolution are sufficient to prevent rotational instability of the degenerate core or white dwarf remnant. (AIP)

• Research Organization: Institute of Astronomy, Cambridge, England
• OSTI ID: 7330133
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 209:3; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANGULAR MOMENTUM
BINARY STARS
EQUILIBRIUM
GIANT STARS
GRAVITATIONAL RADIATION
MASS TRANSFER
RADIATIONS
RED GIANT STARS
ROCHE EQUIPOTENTIALS
STAR EVOLUTION
STARS
STELLAR WINDS
SUPERGIANT STARS
THERMAL EQUILIBRIUM