2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/17435The kinetic theory of a self-gravitating system is considered in the framework of Bhatnager-Gross-Krook model. This approach offers a unique and tractable setup for studying the central, collision-dominated region of the system, as well as its outer almost collisionless part. Stationary non-equilibrium states of the system are considered and several different self-similar solutions are identified.4 pages Latex wsp9.cls. Proceedings Marcel Grossmann IX (World Scientific). Short version: 4 pages, extended version for CD-rom: 13 pagesStatistical MechanicsAstrophysicstext