Evolution of Single Stars. II. Core Helium Burning in Population I Stars

The results of model evolutionary computations are presented for Population I stars of 3, 5, 7, 10 and 15 M_odot. The core helium burning phase of these models is discussed. The models make (or do not make) the well known loops in the H-R diagram during this stage of evolution. The presence and characteristics of these loops are probably related to somedetails of the computational techniques used. The influence of the chemical composition is less pronounced and cannot be meaningfully established at this time.