Evolution of Close Binaries. II.

The evolution of massive binaries is studied in case when the primary component approaches the Roche limit during the hydrogen core burning phase. Conservation of the total mass and angular orbital momentum during the evolution of a binary is assumed. An initial hydrogen content X_0=0.75, and a metal content Z=0.044 are adopted. The adopted hydrogen content is higher than that used in the previous paper (Paczynski 1966) in order to study its influence on the evolution of close binaries. The predicted luminosity and radius excesses of the contact components of semidetached binaries are in reasonable agreement with the observation, although theoretical excesses are probably too small.