Revised interstellar gas models including a collisional drag force

Abstract

Neutrai interstellar particles penetrating into the heliosphere, besides being subject there to specific loss processes, suffer elastic collisions with solar wind protons. The effect of these collisions can be described via two additional forces terms, one acting in radial direction and so reducing the effective gravity and the other in orthoradial direction and so leading to a specific loss of angular momentum of the neutrals. The dynamical particle trajectories hence are changed into non-Keplerians leading to density and temperature distributions differing from those calculated in the past, especially near the sun. This is found from a numerical solution of the appropriate Boltzmann equation and provides new density distributions.