Convection and convective overshooting in stars more massive than 10 M⊙

We examine how the mixing length parameter alpha(p) and the overshooting parameter delta(ov) affect the properties of convective cores and convective envelopes in stars more massive than 10 M-circle dot. First, we show that a larger value of alpha(p) leads to a stronger mixing, a smaller chemical gradient, a higher effective temperature, and a smaller stellar radius. We then find that if a star develops convective core overshooting during the main sequence phase, the star will enter the red (super) giant phase earlier than a star without core overshooting. Finally, we find that a convective envelope leads to a discontinuity of the hydrogen profile above the hydrogen burning shell. Convective envelope overshooting can facilitate the occurrence of blue loop in the Hertzsprung-Russell diagram.