Publications
of the
MPIfR
Optical & Infrared
Interferometry Group
J.M. Winters, T. Le Bertre, L.-A.
Nyman, A. Omont, and K.S. Jeong:
The hydrodynamical structure of
circumstellar envelopes around
low mass-loss rate, low outflow velocity AGB stars
Astronomy and Astrophysics, 388, 609 (2002)
Abstract.
Recent hydrodynamical models (Winters et al. 2000b)
allow the existence of pulsating, large velocity amplitude
Asymptotic Giant Branch (AGB) stars with tenuous dusty circumstellar
shells, which produce low mass-loss rates and simultaneously low wind
velocities. The Semi-regular long-period variable L22 Pup
shows a
broad SiO maser feature at 86 GHz (v=1, J=2-1), indicating an outward
velocity of the material close to the stellar photosphere of at
least 10 km/s, and narrow CO (J=2-1) and (1-0) line profiles
indicating an outflow velocity of the material in the circumstellar
shell of only about 3 km/s. This can be explained in terms of our
hydrodynamical models which provide large velocities in the shocked
stellar atmosphere and low velocities of the circumstellar outflow.
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