The solar wind

Heating of the extended solar corona leads to high proton temperatures and relatively low electron temperatures. This is due to the low heat conductivity in the proton gas as compared to the electrons. A large fraction of the energy flux added to the electrons is conducted back into the transition region, whereas most of the energy flux deposited in the protons is lost as kinetic and gravitational solar wind energy flux. How this energy flux is divided between gravitational and kinetic energy flux (i.e, how large are the particle fluxes and flow speeds) depend upon details of the heating process. The low electron temperature that results in models with significant proton heating is consistent with a small polarization electric field and a small electron heat flux in the solar wind acceleration region.