Issue |
A&A
Volume 369, Number 2, April II 2001
|
|
---|---|---|
Page(s) | 574 - 588 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20010127 | |
Published online | 15 April 2001 |
Mass-loss predictions for O and B stars as a function of metallicity
1
Astronomical Institute, Utrecht University, PO Box 80000, 3508 TA Utrecht, The Netherlands
2
Astronomical Institute "Anton Pannekoek", University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
3
SRON Laboratory for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
Corresponding author: Jorick S. Vink, j.vink@ic.ac.uk
Received:
24
July
2000
Accepted:
17
January
2001
We have calculated a grid of massive star wind models and
mass-loss rates for a wide range of metal abundances between
.
The calculation of this grid completes
the Vink et al. (2000) mass-loss recipe with an additional
parameter Z.
We have found that the exponent of the power law dependence of mass loss
vs. metallicity is constant in the range between 1/30 ≤
≤ 3.
The mass-loss rate scales as
with
for stars with
K, and
for
the B supergiants with
K. Taking also into account the metallicity
dependence of
, using the power law dependence
from Leitherer et al. (1992),
the overall result of mass loss as a function of metallicity can be represented by
for stars with
K, and
for B supergiants with
K.
Although it is derived that the exponent of the mass loss vs. metallicity
dependence is constant over a large range in Z, one should
be aware of the presence of bi-stability jumps at specific
temperatures. Here the character of the line driving changes
drastically due to recombinations of dominant metal species
resulting in jumps in the mass loss.
We have investigated the physical origins of these jumps and have
derived formulae that combine mass loss recipes for
both sides of such jumps. As observations of different galaxies
show that the ratio Fe/O varies with metallicity, we make a distinction
between the metal abundance Z derived on the basis of iron or oxygen
lines.
Our mass-loss predictions are successful in explaining
the observed mass-loss rates for Galactic and Small Magellanic Cloud
O-type stars, as well as in predicting the observed Galactic
bi-stability jump. Hence, we believe that our predictions are reliable
and suggest that our mass-loss recipe be used in future
evolutionary calculations of massive stars at different metal
abundance.
A computer routine to calculate mass loss is publicly
available.
Key words: stars: early-type / stars: mass-loss / stars: supergiants / stars: winds / stars: evolution
© ESO, 2001
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