The Angular Momentum of the Solar Wind

Abstract

The flux of angular momentum associated with low-frequency plasma fluctuations in the solar wind is considered. The transverse A]fvén waves, for which there are no fluctuations in the density, exert an apparent torque on the solar-wind plasma that is in the direction to increase the corotation of the solar wind but is negligible compared with the torque exerted by the mean magnetic field. On the other hand, waves that possess density fluctuations, such as the fast magnetosonic mode of linearized magneto- hydrodynamics, can contribute a flux of angular momentum that is comparable to the mean torque exerted on the solar wind. This contribution is proportional to the product of the mean solar-wind den- sity, the mean radial velocity, the square of the Alfvén speed, and the mean square of the density fluctua- tions divided by the square of the mean density