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TU Berlin

Multi-dimensional wind models for carbon stars

Dr. Peter Woitke (Sterrewacht Leiden, Niederlande)

Donnerstag, den 10.6.2004 um 10 Uhr c.t., PN-114


New multi-dimensional models for dusty winds from C-stars are presented, which include hydrodynamics with radiation pressure on dust grains, chemistry, time-dependent dust formation and simplified grey radiative transfer (same level of approximation as in Fleischer et al. 1995). The modelling of these processes in 2D (using spherical coordinates i.e. assuming axisymmetry) reveals new insight into the chaotic nature of dust-driven winds:

  1. Radial dust shells are apparently Rayleigh-Taylor unstable at their outer boundary, where the opacity drops quickly.
  2. The dust formation and wind acceleration may proceed in a much more complicated way as compared to 1D models. Excited by hydrodynamical, radiative and thermal instabilities, dust forms from time to time in only limited areas close to the star. These clouds are then accelerated outward by radiation pressure which creates gaps in the dust formation zone. These gaps are refilled not only by matter from the inside, but also by dust-free matter from the outside which falls back. A highly dynamical and turbulent dust formation zone is created in this way, which - in return - again bears a strongly inhomogeneous dust distribution.

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