Cool Stars 14 - Submitted Abstract # 167
This version created on 05 October 2006

Atmospheric dynamics and the mass loss process in red supergiants


Eric Josselin, GRAAL-Universite Montpellier II
Bertrand Plez, GRAAL-Universite Montpellier II

We present high-resolution visible spectroscopy of a sample of red
supergiants.  We observe large velocity gradients, characterizing both
upward and downward supersonic motions, which are time variable, on
time scales of a few hundreds days.  These convective motions must
generate turbulent pressure, which will strongly decrease the
effective gravity.  We suggest that this decrease, combined with
radiative pressure on molecular lines, initiate the mass loss in red
supergiant stars.

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