The formation of a massive black hole in the center of a dense star cluster

The evolution of a disklike subcluster of low-mass stars formed from the gas released during inelastic collisions in a dense star cluster is studied. The subcluster evolution due to elastic and inelastic stellar collisions of disk and cluster stars and of disk stars with each other are examined. The processes of possible increases in subcluster disk stellar mass by gas accretion in a thin gas layer and by the coalesence of disk stars are shown to be unimportant. The stellar mass remains low throughout the period of subcluster evolution until the onset of instability. The contraction of a self-gravitating subcluster of new stars after the instability moment is discussed. It is shown that dynamical friction can be an important mechanism of angular momentum loss during the subcluster contraction. It is found that the collapse of the subcluster leads to the formation of a massive black hole.