Key points are not available for this paper at this time.
Spiral patterns that survive for about three "galactic rotations" have been obtained with the model of a sell-gravitating system recently described. These patterns were obtained in the "gas component of a system that consisted of "gas" and "stars," with "stars" being created out of the "gas" in a manner reminiscent of the natural processes in galaxies. The importance of computer models displaying persistent spiral patterns is that they may be used for experiments to see how various modifications affect the persistence or appearance of the spiral patterns. Several experiments were carried out to determine the roles of the constituent parts of the system Spiral patterns in the "gas" component appear to be driven by asymmetries in the stellar background.
Miller et al. (Tue,) studied this question.