The non-linear evolution of strange-mode instabilities

Numerical simulations of the evolution of strange-mode instabilities into the non-linear regime have been performed for massive objects and Wolf--Rayet stars. Velocity amplitudes above 102 km s−1 can be reached which exceed the escape velocity and imply mass loss for massive objects. Although for Wolf--Rayet stars direct mass loss is not observed, the velocity field established by the instability may be sufficient to initiate a line-driven wind. The results are sensitive to the numerical treatment of the problem.