Non-Maxwellian Velocity distribution functions associated with steep temperature gradients in the solar transition region

Abstract

We show that, in the presence of the steep temperature gradients characteristic of EUV models of the solar transition region, the electron and proton velocity distribution functions are non-Maxwellian and are characterized by high energy tails. We estimate the magnitude of these tails for a model of the transition region and compute the heat flux to be a maximum of 30% greater than predicted by collision-dominated theory.