Radiation-driven winds of hot luminous stars. IV. The influence of multi-line effects.

The paper presented here investigates an effect neglected in prior calculations of radiation driven wind models in this series of publications - the influence of multi-line effects. These effects arise through the possibility that photons can be processed more than once in different transitions when propagating through the wind and are essential for hot stars as both the line density and the line strengths are large in the UV. Three different methods - the Sobolev-, comoving frame and Monte-Carlo-approach - have been used to investigate the processes as a whole and some approximations. The influence of these effects is calculated for O-star-models. It turns out that the treatment of the line force in the author's prior calculations overestimates this quantity and that the actual line force is only of order 70% to 90% compared to the former results. With the modified line force, both mass loss rate and terminal velocity are reduced in selfconsistent wind models (ζ Pup, τ Sco) compared with the results of Pauldrach (1987).