Issue |
A&A
Volume 407, Number 1, August III 2003
|
|
---|---|---|
Page(s) | 191 - 206 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20030693 | |
Published online | 17 November 2003 |
Self-consistent modeling of the outflow from the O-rich Mira IRC –20197
1
LERMA, UMR 8112, Observatoire de Paris, 61 Av. de l'Observatoire, 75014 Paris, France
2
Technische Universität Berlin, Zentrum für Astronomie und Astrophysik, Sekr. PN 8-1, Hardenbergstr. 36, 10623 Berlin, Germany
3
Deutsches Zentrum für Luft– und Raumfahrt, Institute of Space Sensor Technology and Planetary Exploration, Rutherfordstr. 2, 12489 Berlin, Germany
4
IRAM, 300 rue de la Piscine, 38406 St. Martin d'Hères, France
Corresponding author: K. S. Jeong, Kyung.Jeong@obspm.fr
Received:
20
January
2003
Accepted:
6
May
2003
We present a self–consistent time–dependent model for the
oxygen–rich Mira variable IRC –20197. This model includes a consistent
treatment of the interactions among hydrodynamics, thermodynamics,
radiative transfer, equilibrium chemistry, and heterogeneous dust
formation with TiO2 nuclei. The model is determined by the
stellar parameters, stellar mass ,
stellar luminosity
, stellar
temperature
, and solar abundances of the
elements. The pulsation of the star is simulated by a piston at the
inner boundary where the velocity varies sinusoidally with a period of
and an amplitude of
. Based on the atmospheric structure resulting from this
hydrodynamic calculation at different phases, we have performed
angle– and frequency–dependent continuum radiation transfer
calculations, which result in the spectral energy distributions at
different phases of the pulsation cycle and in synthetic light curves
at different wavelengths. These are in good agreement with the
infrared observations of IRC –20197. The model yields a time averaged
outflow velocity of
and an average mass loss
rate of
which are in good
agreement with the values derived from radio observations.
Furthermore, the chemical composition of the resulting grains is
discussed.
Key words: hydrodynamics / radiative transfer / stars: winds, outflows / stars: circumstellar matter / stars: AGB and post-AGB / stars: individual: IRC –20197
© ESO, 2003
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