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TwitterA&A 442, 587-596 (2005)
DOI: 10.1051/0004-6361:20052862
On the metallicity dependence of Wolf-Rayet winds
Jorick S. Vink1 and A. de Koter21 Imperial College, Blackett Laboratory, Prince Consort Road, London, SW7 2AZ, UK
e-mail: jsv@astro.keele.ac.uk
2 Astronomical Institute "Anton Pannekoek", University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
(Received 10 February 2005 / Accepted 13 July 2005 )
Abstract
We have performed a pilot study of mass loss predictions
for late-type Wolf-Rayet (WR) stars as a function of metal
abundance, over a range between
Z
. We
find that the winds of nitrogen-rich Wolf-Rayet stars are
dominated by iron lines, with a dependence of mass loss on Z
similar to that of massive OB stars. For more evolved, carbon-rich, WR
stars the wind strength is also found to be dependent on the Fe abundance,
so that they depend on the chemical environment of the host galaxy, but with a
mass loss metallicity dependence that is less steep than for OB stars.
Our finding that WR mass loss is Z-dependent is a new one, with
important consequences for black hole formation and X-ray population
studies in external galaxies.
A further finding of our study is that the Z dependence of
C-rich WR stars becomes weaker
at metallicities below
1/10, and mass loss
no longer declines once the metal abundance drops below (Z/
) 
10-3.
This is the result of an increased importance of
radiative driving by intermediate mass elements, such as carbon.
In combination with rapid rotation and/or proximity to the
Eddington limit - likely to be relevant for massive Population III stars - this effect
may indicate a role for mass loss in the appearance and evolution of these objects, as well as a potential role
for stellar winds in enriching the intergalactic medium of the early Universe.
Key words: stars: Wolf-Rayet -- stars: early-type -- stars: mass-loss -- stars: winds, outflows -- stars: evolution
SIMBAD Objects
© ESO 2005