Fig. A1. Rate of change of the mean kinetic energy for stars of the three mass groups of the rigidly rotating model with , , and ; 1 - kinetic energy of stars with the mass of a star , 2 - with the mass of a star , and 3 - with the mass of a star . The two groups of heavy stars lose kinetic energy while the group of lightest stars gains an approximately corresponding amount of kinetic energy. The mean slope of the curves will result in energy equipartition after about 20 rotation periods. This result suggests that interparticle collisions do not play a significant role for instabilities studied in the paper.