TY  - CONF
A1  - de Koter, A.
A1  - Vink, J. S.
A1  - Muijres, L.
T1  - Constraints on wind clumping from the empirical mass-loss vs. metallicity relation for early-type stars
N2  - We present the latest results on the observational dependence of the mass-loss rate in stellar winds of O and early-B stars on the metal content of their atmospheres, and compare these with predictions. Absolute empirical rates for the mass loss of stars brighter than 10$^{5.2} L_{\odot}$, based on H$\alpha$ and ultraviolet (UV) wind lines, are found to be about a factor of two higher than predictions. If this difference is attributed to inhomogeneities in the wind this would imply that luminous O and early-B stars have clumping factors in their H$\alpha$ and UV line forming regime of about a factor of 3--5. The investigated stars cover a metallicity range $Z$ from 0.2 to 1 $Z_{\odot}$. We find a hint towards smaller clumping factors for lower $Z$. The derived clumping factors, however, presuppose that clumping does not impact the predictions of the mass-loss rate. We discuss this assumption and explain how we intend to investigate its validity in more detail.
Y1  - 2008
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/1605
UR  - https://nbn-resolving.org/urn:nbn:de:kobv:517-opus-17736
ER  -