Interacting Binaries: Topics In Close Binary Evolution

Abstract

The author considers some basic aspects of the celestial mechanics of binary systems, the meaning and limitations of the Roche-lobe concept, the changes in orbital period and orbital separation that may be induced by processes of mass loss and mass transfer in binary sytems. He gives a classification of the various types of close binary systems, concentrating most of our attention to systems in which at least one component is an evolved star. He describes in some detail the various types of X-ray binaries and binary radio pulsars. Then he summarizes the evolution of single stars and classifies the types of remnants produced by this evolution. The various possible types of evolution of a close binary are described, as a function of initial primary mass, mass ratio and orbital separation. A comparison with observed types of systems is presented. The author then considers more exotic types of close binary evolution (non-conservative), their common envelope evolution, and discusses the products of this evolution: cataclysmic variables, low-mass X-ray binaries, double white dwarfs, binary radio pulsars, and runaway pulsars. Then the evolution of a neutron star as companion to a normal star, and their final results: binary and millisecond pulsars, are discussed. Finally the author gives statistics of binary evolution in the Galaxy, and in open clusters.