Hydrodynamic Model Calculations for Supermassive Stars. II. The Collapse and Explosion of a Nonrotating 5.2 X 10~ M0 Star

Summary. The dynamical evolution of a 5.2 x i0 M0 supermassive star is followed by solving numerically the general relativistic hydrodynamic equations. After initial quasistatic contraction general relativistic collapse below the static main-sequence radius takes place. The radiation pressure which is built up during the collapse phase by fast HCNO burning halts and reverses the collapse into a violent explosion which results in the complete dispersion of the star. Together with the results of an earlier paper it is concluded that - unless exotic damping mechanisms are invoked - relaxation oscillations as proposed by Fowler cannot occur in nonrotating supermassive stars. The kinematics and energetics of the explosion suggest that a possible mechanism is found which may serve to explain the explosion phenomena in peculiar galaxies like M 82 and NGC 1275. Key words: supermassive stars - exploding galaxies - general relativistic dynamical instability