## Rotating massive O stars with non-spherical 2D winds

**Patrick E. MÃ¼ller (1,2), Jorick S. Vink (1)**

(1) Armagh Observatory, Armagh, Northern-Ireland, UK,

(2) School of Physical and Geographical Sciences, Keele University, Staffordshire, UK

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

theta. 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 theta. 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 40

M_sun O5-V main sequence star as well as to a 60 M_sun O-giant star,

and we compare our results to previous studies that are extensions of the

Castor et al. (1975, ApJ, 195, 157) 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 (2000, A&A, 361, 159) 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.

**Reference: **A&A, in press

Status: Manuscript has been accepted

**Weblink: **http://arxiv.org/abs/1402.5929

**Comments: **20 pages, 4 figures, 7 tables

**Email: **p.e.mueller@gmx.com