Structure and evolution of very close binary systems. I - Structure equations including rotational and tidal distortions and calculations for 2, 1, and 0.65 solar-mass zero-age main-sequence stars

Abstract

A method is developed which allows an efficient and accurate investigation of the structure and evolution of a rotationally and tidally distorted star in a close binary system. The method involves no division into different approximation regimes, and the structure equations are written in essentially the same form as the one for spherical stars. The explicit effects of the distortions are included through basically just one correction factor which can be readily calculated. We also discuss in some detail the envelope integration in the case of superradiabatic convection. Models for zero-age main-sequence stars of 2, 1, and 0.65 M/sub sun/ are computed as a check on our formulation and compared with those obtained using other methods.