Abstract: A model for rotating binary stars is presented. The potential of the primary is derived and the gravitational acceleration is simulated. We only consider the first order in the potential of the gravitational potential. The results show that the gravitational acceleration reaches the maximum value at polar region and goes down the minimum value at the top of the longest axis. Moreover, due to the combined effect of the spin and tide, the effective temperature of the two components decreases for some extent. As a result, the life time of the two components is prolonged on their main sequence.

Key words: gravitational potential, rotation, stellar evolution