On the effects of strong encounters in stellar systems. I - A basis for treating anisotropic systems
Abstract
In the present investigation, a foundation is provided for studying the effects of strong encounters in anisotropic stellar systems. The simplifying assumption of isotropic velocity distributions is removed from the discussion of strong binary encounters, and transition rates which distinguish between velocity changes parallel to and perpendicular to the initial velocity of a star are obtained. The transition rate associated with binary encounters is considered, taking into account the differential transition rate, an analysis of the allowed ranges of the physical variables, and the integrated transition rate. Attention is given to escape rates and energy-loss rates, an evolution equation for the distribution function of test stars, and the isotropoic field star approximation.