Simulation of the evolution of stellar systems

Abstract

Computer models for isolated disk galaxies and for infi nite doubly periodic stellar systems are used to study the self-consistent motion of large numbers of interacting stars as they move in the plane of the galactic disk. The doubly periodic model is used to investigate the develop ment of the gravitational instability for a plane stellar system. The results obtained show that the initial con densations which form are about two Jeans lengths in diameter. An isolated, initially cold, balanced disk is found to be violently unstable. Adding a sciffcient amount of ve locity dispersion will stabilize all small-scale disturb ances. Most disks investigated are found to be unstable against slowly growing long wavelength modes, and after about two rotations the disks tend to assume a bar- shaped structure. It is also found that the final mass distribution for most disks can be closely approximated by an exponential variation irrespective of the initial mass distribution.