Radiation driven winds with rotation: the oblate finite disc correction factor
Abstract
We have incorporated the oblate distortion of the shape of the star due to the stellar rotation, which modifies the finite disk correction factor (f_{D}) in the mCAK hydrodynamical model. We implement a simplified version for the f_{D} allowing us to solve numerically the nonlinear mCAK momentum equation. We solve this model for a classical Be star in the polar and equatorial directions. The star's oblateness modifies the polar wind, which is now much faster than the spherical one, mainly because the wind receives radiation from a larger (than the spherical) stellar surface. In the equatorial direction we obtain slow solutions, which are even slower and denser than the spherical ones. For the case when the stellar rotational velocity is about the critical velocity, the most remarkable result of our calculations is that the density contrast between the equatorial density and the polar one, is about 100. This result could explain a longstanding problem on Be stars.
 Publication:

Active OB Stars: Structure, Evolution, Mass Loss, and Critical Limits
 Pub Date:
 July 2011
 DOI:
 10.1017/S1743921311010015
 arXiv:
 arXiv:1009.5336
 Bibcode:
 2011IAUS..272...83A
 Keywords:

 stars: rotation;
 stars: winds;
 outflows;
 stars: earlytype;
 stars: emissionline;
 Be;
 Astrophysics  Solar and Stellar Astrophysics
 EPrint:
 2 pages, to appear in the proceedings of the IAUS 272 on "Active OB stars: structure, evolution, mass loss and critical limits" (Paris, July 1923, 2010), Cambridge University Press. Editors C. Neiner, G. Wade, G. Meynet and G. Peters