2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/2158The kinetic theory is used to study the evolution of the self-gravitating disk of planetesimals. The effects of frequent collisions between planetesimals are taken into account by using a Krook integral in the Boltzmann kinetic equation. It is shown that as a result of an aperiodic collision-dissipative instability of small gravity disturbances the disk is subdivided into numerous dense fragments. These can eventually condense into the planetary sequence.3 pages, 1 figure, presented by E. Griv at the IAU Symp. 202, Manchester, UK, 2000Astrophysicstext