Solar Wind Models Based on Exospheric Theory
Abstract
Due to the rare collisions exospheric theory should be well suited to describe the solar wind. Nevertheless, according to the work of Chamberlain it was thought that evaporation of particles cannot lead to the transonic flow present in the solar wind. Chamberlain assumed the radial electric field to be equal to that in a static atmosphere. However, the radial electric field has to be determined selfconsistently by the quasineutrality condition. Then one can construct transonic solutions, even if the particles are collisionless. In the models the spherically symmetric outflow of an electron-proton plasma is considered in which the protons are collisionless. In one model the electrons are also assumed to be collisionless while in some others an isotropic electron temperature was explicitly prescribed. From comparison of the models with observation one can draw the following conclusions about the real solar wind: 1. while in the quiescent solar wind nonthermal heating of the protons may not be present it seems probable that wave particle interactions or ether nonstationary effects lead to a fluidlike behaviour of the electrons even at qulet conditions. 2. the observed fact, that the protons have a lower velocity dispersion in the solar than in the antisolar direction is caused by a truncation of the distribution function because of the evaporation of the particles in the gravitational field.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 1970
- Bibcode:
- 1970A&A.....6..219J