TY  - JOUR
A1  - Sander, Andreas Alexander Christoph
A1  - Vink, Jorick S.
A1  - Hamann, Wolf-Rainer
T1  - Driving classical Wolf-Rayet winds
T2  - Monthly notices of the Royal Astronomical Society
N2  - Classical Wolf-Rayet (cWR) stars are at a crucial evolutionary stage for constraining the fates of massive stars. The feedback of these hot, hydrogen-depleted stars dominates their surrounding by tremendous injections of ionizing radiation and kinetic energy. The strength of a Wolf-Rayet (WR) wind decides the eventual mass of its remnant, likely a massive black hole. However, despite their major influence and importance for gravitational wave detection statistics, WR winds are particularly poorly understood. In this paper, we introduce the first set of hydrodynamically consistent stellar atmosphere models for cWR stars of both the carbon (C) and the nitrogen (N) sequence, i.e. WC and WN stars, as a function of stellar luminosity-to-mass ratio (or Eddington Gamma) and metallicity. We demonstrate the inapplicability of the CAK wind theory for cWR stars and confirm earlier findings that their winds are launched at the (hot) iron (Fe) opacity peak. For log Z/Z(circle dot) > -2, Fe is also the main accelerator throughout the wind. Contrasting previous claims of a sharp lower mass-loss limit forWR stars, we obtain a smooth transition to optically thin winds. Furthermore, we find a strong dependence of the mass-loss rates on Eddington Gamma, both at solar and subsolar metallicity. Increases inWCcarbon and oxygen abundances turn out to slightly reduce the predicted mass-loss rates. Calculations at subsolar metallicities indicate that below the metallicity of the Small Magellanic Cloud, WR mass-loss rates decrease much faster than previously assumed, potentially allowing for high black hole masses even in the local Universe.
KW  - stars: atmospheres
KW  - stars: early-type
KW  - stars: fundamental parameters
KW  - stars: mass-loss
KW  - stars: winds, outflows
KW  - stars: Wolf-Rayet
Y1  - 2019
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/57887
SN  - 0035-8711
SN  - 1365-2966
VL  - 491
IS  - 3
SP  - 4406
EP  - 4425
PB  - Oxford Univ. Press
CY  - Oxford
ER  -