Non-spherical dust driven winds of slowly rotating AGB stars

E.A. Dorfi and S. Höfner

We propose a new mechanism to explain an asymmetric mass loss for C-rich asymptotic giant branch (AGB)-stars based on the effect how rotation modifies dust driven winds. Even small deviations from spherical symmetry introduced by slow rotations are amplified in the zone of dust condensation due to the non-linear behaviour and the strong temperature and density dependence of the dust formation process. This mechanism leads to a preferential mass loss with higher velocities in the equatorial plane. Depending on the rotation rate we calculate for typical AGB stars stationary dust driven winds and present the rotation modulated solutions as a function of the polar angle. The mass loss rate can differ by large factors comparing the polar to the equatorial region. This mechanism provides also a simple explanation for the widely observed asymmetries found in the shapes of planetary nebulae.

A&A 313, 605