Semiconvection in the Core-Helium Phase of Stellar Evolution

A treatment of the expansion by convective overshooting of the helium-burning convective cores in stars over a wide mass range is described. A semiconvective zone forms outside the core, and this zone has been followed through its evolution. In some circumstances there is a fully convective region embedded in this zone. To illustrate the semiconvection treatment, the core-helium-burning phases of S and 1.5 , Population I stars have been computed to near exhaustion of helium in the core.