Radiation driven winds of hot luminous stars. VII. The evolution of massive stars and the morphology of stellar wind spectra.

A grid of wind models along evolutionary tracks of massive O stars is calculated using the improved radiation driven wind theory developed recently by Pauldrach et al. (1986), Pauldrach (1987), and Pauldrach and Herrero (1988). The intention of the present paper is to investigate the change of spectral morphology during the course of stellar evolution. The results show that the improved stellar wind models can describe the significantly different observed behavior of the profiles of the Si IV line with respect to those of C IV and N V as a function of spectral type and luminosity class. The physical reason for this effect is explained.