Star Formation in Galactic Nuclei

Abstract

The star formation in galactic open clusters leads, as a rule, to a complete disruption of the latter (Tutukov, 1978) because of the shallow potential wall of these clusters. The matter of dense galactic nuclei is in deep potential walls what drastically changes the star formation regime. The numerical dynamical model of the star formation in galactic nuclei with the mass 6 109 M⊙ and the radius ~ 430pc was proposed by Loose et al (1982). It includes old and newly-formed stars, gas and dust distributed initially as in the center of our Galaxy. The model takes into account the star formation, supernova explosions, stellar winds, the turbulent motion of the gas component, non-grey radiative energy transfer, the influx of gas from old stars and from the outside. The main parameter of our model is the time of dissipation of the kinetic energy of the gas component Td. Supernova explosions are the main source of this energy. The results of numerical experiments help to point out two main regimes of the star formation in galactic nuclei: stationary and bursting. In the stationary regime the rate of the star formation is constant and it equals to the rate of the gas input. The formation of a long-living superstar is possible in this case (Krügel, Tutukov, 198b). In the bursting regime the periods of an active star formation alternate with those of almost a complete absence of the star formation. The main reason for supressing the star formation process is supernova explosions which throw the gas out of the galactic nuclei.