Magnetic braking in cataclysmic binary systems

Abstract This paper studies the angular momentum loss due to a magnetically coupled stellar wind of the cool secondary and its effect on the evolution of the cataclysmic binary system. Special attention is paid to the following differences between the binary and single star cases: the stellar wind in a binary system will be enhanced by the tidal effect and rotation of the system, and the angular momentum of a binary member consists of a rotational, and a much greater orbital components. It is shown that owing to the mass loss rate and wind velocity of the secondary both being very small, the angular momentum loss due to magnetic braking is far too insignificant to drive the evolution of cataclysmic binaries with periods longer than 3hr.