Issue |
A&A
Volume 384, Number 2, MarchIII 2002
|
|
---|---|---|
Page(s) | 452 - 459 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20020022 | |
Published online | 15 March 2002 |
An improved mass-loss description for dust-driven superwinds and tip-AGB evolution models
1
Astronomy Centre, CPES, University of Sussex, Falmer, Brighton BN1 9QJ, UK
2
Technische Universität Berlin, Zentrum für Astronomie und Astrophysik, PN 8-1, Hardenbergstr. 36, 10623 Berlin, Germany
3
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
Corresponding author: A. Wachter, a.c.wachter@sussex.ac.uk
Received:
7
November
2001
Accepted:
4
January
2002
We derive an improved description of dust-driven stellar
mass-loss for the cool winds of carbon-rich tip-AGB stars. We use
pulsating wind models in which the mass loss is driven by radiation
pressure on dust grains, for C-rich chemistry. From a larger set of
these models, selected for representative dynamical (pulsational
velocity amplitude , period P) and chemical (the
abundance ratio) input
parameters, an improved approximative mass-loss formula has been
derived which depends only on the stellar parameters (effective
temperature Teff, luminosity L and mass M). Due to the
detailed consideration of the chemistry and the physics of the dust
nucleation and growth processes, there is a particularly strong
dependence of the mass-loss rate
(in
yr) on
Teff:
. The dependence of the model mass-loss on
the pulsational period has explicitly been accounted for in
connection with the luminosity dependence, by applying an observed
period–luminosity relation for C-rich Miras. We also apply the
improved mass-loss description to our evolution models, and we
revisit their tip-AGB mass-loss histories and the total masses lost,
in comparison to our earlier work with a preliminary mass-loss
description. While there is virtually no difference for the models
in the lower mass range of consideration (
to
), we now find more realistic, larger superwind
mass-loss rates for larger stellar masses: i.e.,
between
≈
and
/yr for Mi
between 1.85 and 2.65
, removing between 0.6 and
1.2
, respectively, during the final 30 000 yrs on the
tip-AGB.
Key words: stars: carbon / stars: circumstellar matter / stars: evolution / stars: interiors / stars: late-type / stars: mass loss
© ESO, 2002
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