The Evolution of Low and Intermediate Mass Binary Systems

Abstract

During phases of nuclear burning the radius of the star increases. If the star is a member of a close binary, this increase is limited by the presence of the companion. If a well determined critical value of the radius is exceeded mass transfer can occur from one component to the other, or mass can even leave the system, or may be stored in rings or disks. The computation of these mass transfer stages is only possible when certain approximations are accepted. Hydrodynamics and deviations from spherical symmetry (rotational and tidal effects) are generally not considered and the orbit is usually considered as circular. The rotation of the components is assumed to be synchronized with the orbital motion. The evolution of close binary systems depends on the masses of the components, the mass ratio and the orbital period.