A hydrodynamic scheme for two-component winds from hot stars

¹ Astronomický ústav, Akademie věd České republiky, 251 65 Ondřejov, Czech Republic e-mail: votruba@sunstel.asu.cas.cz
² Ústav teoretické fyziky a astrofyziky, Přirodověcká fakulta, Masarykova univerzita, Kotlářská 2, 611 37 Brno, Czech Republic
³ Astrophysik, Institut für Physik, Universität Potsdam, Am Neuen Palais 10, 14469 Potsdam, Germany e-mail: afeld@astro.physik.uni-potsdam.de

Received: 11 September 2006
Accepted: 21 June 2007

Abstract

Aims.We have developed a time-dependent two-component hydrodynamics code to simulate radiatively-driven stellar winds from hot stars.

Methods.We use a time-explicit van Leer scheme to solve the hydrodynamic equations of a two-component stellar wind. Dynamical friction due to Coulomb collisions between the passive bulk plasma and the line-scattering ions is treated by a time-implicit, semi-analytic method using a polynomial fit to the Chandrasekhar function. This gives stable results despite the stiffness of the problem.

Results.This method was applied to model stars with winds that are both poorly and well-coupled. While for the former case we reproduce the mCAK solution, for the latter case our solution leads to wind decoupling.