Binary fission in damped rotating polytropes

The forms of equilibrium and the mode of fission of damped, differentially-rotating polytropes are calculated using the SPH method. The damping used conserves total angular momentum and angular momentum per unit mass. The equilibrium forms are similar to the classical liquid, viscous sequences with a transition from axisymmetric to approximately ellipsoidal forms when |T/|W|0. 14|⁠. Sequences with n = 0. 5 end by fission into two condensed bodies which form a close binary. Sequences with n = 1. 5 undergo a fission which produces a stream with ∼ 0. 25 of the total mass. The accuracy of the calculations has been estimated by running sequences with different particle numbers, initial particle positions and variations in the choice of the smoothing length. These parameters produce sequences which are very similar, up to the point of fission, but the details of the binary (or stream) vary widely.