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Astron. Astrophys. 343, 251-260 (1999)

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Numerical simulations of stellar winds: polytropic models

R. Keppens and J.P. Goedbloed

FOM-Institute for Plasma-Physics Rijnhuizen, P.O. Box 1207, 3430 BE Nieuwegein, The Netherlands (e-mail: keppens@rijnh.nl; jpg@rijnh.nl)

Received 8 August 1998 / Accepted 2 December 1998


We discuss steady-state transonic outflows obtained by direct numerical solution of the hydrodynamic and magnetohydrodynamic equations. We make use of the Versatile Advection Code, a software package for solving systems of (hyperbolic) partial differential equations. We proceed stepwise from a spherically symmetric, isothermal, unmagnetized, non-rotating Parker wind to arrive at axisymmetric, polytropic, magnetized, rotating models. These represent 2D generalisations of the analytical 1D Weber-Davis wind solution, which we obtain in the process. Axisymmetric wind solutions containing both a `wind' and a `dead' zone are presented.

Since we are solving for steady-state solutions, we efficiently exploit fully implicit time stepping. The method allows us to model thermally and/or magneto-centrifugally driven stellar outflows. We particularly emphasize the boundary conditions imposed at the stellar surface. For these axisymmetric, steady-state solutions, we can use the knowledge of the flux functions to verify the physical correctness of the numerical solutions.

Key words: Sun: solar wind – methods: numerical – Magnetohydrodynamics (MHD)

Send offprint requests to: R. Keppens

© European Southern Observatory (ESO) 1999

Online publication: March 1, 1999