Stellar evolution in the upper Hertzsprung-Russell diagram

Evolutionary computations for massive stars, including mass loss and overshooting from convective cores, are presented. Using these computations, a coherent picture of the evolution of massive stars in the upper H-R diagram is given. Different formation mechanisms for various groups of luminous stars are discussed. Eta Carinae is interpreted as a very massive star suffering from a high mass loss, induced by vibrational instabilities. The Hubble-Sandage variables are divided into two groups: the more luminous ones are interpreted as Eta Carinae-like objects, while the less luminous ones are post-red supergiant stars. The boundary masses of progenitors of W-R systems formed through different scenarios are discussed. The observed ratio of W-R stars to O stars is discussed.