Nonlinear spherical Alfven waves.
Abstract
We present an onedimensional numerical study of Alfven waves propagating along a radial magnetic field. Neglecting losses, any spherical Alfven wave, no matter how small its initial amplitude is, becomes nonlinear at sufficiently large radii. From previous simulations of Alfven waves in plane parallel atmospheres we did expect the waves to steepen and produce current sheets in the nonlinear regime, which was confirmed by our new calculations. On the other hand we did find that even the least nonlinear waves were damped out almost completely before 10 solar radii. A damping of that kind is required by models of Alfven wavedriven winds from old lowmass stars as these winds are mainly accelerated within a few stellar radii.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 March 1998
 DOI:
 10.1046/j.13658711.1998.t01129511160.x
 arXiv:
 arXiv:astroph/9709222
 Bibcode:
 1998MNRAS.295...55T
 Keywords:

 Magnetohydrodynamic Waves;
 Wave Propagation;
 Spherical Waves;
 Stellar Magnetic Fields;
 Stellar Winds;
 Nonlinear Equations;
 Current Sheets;
 Computational Astrophysics;
 Astronomical Models;
 Astrophysics;
 Astrophysics
 EPrint:
 12 pages, 14 figures, LaTeX MN style, to appear in MNRAS