2014A&A...564A..57M -
Astronomy and Astrophysics, volume 564A57-57 (2014/4-1)
Rotating massive O stars with non-spherical 2D winds.
MUELLER P.E. and VINK J.S.
Abstract (from CDS):
We present solutions for the velocity field and mass-loss rates for 2D axisymmetric outflows, as well as for the case of mass accretion through the use of the Lambert W-function. For the case of a rotating radiation-driven wind the velocity field is obtained analytically using a parameterised description of the line acceleration that only depends on radius r at any given latitude θ. The line acceleration g(r) is obtained from Monte-Carlo multi-line radiative transfer calculations. The critical/sonic point of our equation of motion varies with latitude θ. Furthermore, an approximate analytical solution for the supersonic flow of a rotating wind is derived, which is found to closely resemble the exact solution. For the simultaneous solution of the mass-loss rate and velocity field, we use the iterative method of our 1D method extended to the non-spherical 2D case. We apply the new theoretical expressions with our iterative method to the stellar wind from a differentially rotating 40M
☉ O5-V main sequence star as well as to a 60M
☉ O-giant star, and we compare our results to previous studies that are extensions of the Castor et al. (
1975ApJ...195..157C) CAK formalism. Next, we account for the effects of oblateness and gravity darkening. Our numerical results predict an equatorial decrease of the mass-loss rate, which would imply that (surface-averaged) total mass-loss rates are lower than for the spherical 1D case, in contradiction to the Maeder & Meynet (
2000A&A...361..159M) formalism that is oftentimes employed in stellar evolution calculations for rotating massive stars. To clarify the situation in nature we discuss observational tests to constrain the shapes of large-scale 2D stellar winds.
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Journal keyword(s):
hydrodynamics - methods: analytical - stars: early-type - stars: mass-loss - stars: rotation - methods: numerical
Simbad objects:
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