The calculation of a collapse of iron-oxygen stellar core in one-group energy approximation

Results of the calculation of a gravitational collapse of the iron-oxygen c ore of a star with mass 2M(.) by the new method proposed by one of the auth ors (Aksenov 1998a) are presented. This method incorporates the integration of hydrodynamic equations of matter, equations of beta-processes and therm onuclear reactions kinetics, and the solution of transfer equations for dif ferent kinds of neutrino with allowance for the dependence of radiation int ensities on the direction of motion and energy of particles. The calculatio ns are carried out in the one-group energy approximation and compared to th ose obtained earlier by Nadyozhin (1978). The main result of this work is t he presence of a narrow peak with a characteristic width of similar to 10 m s in the light curve, which enables one to determine the upper bound on the rest mass of electron neutrino at a level of similar to 2 eV in the case o f detection of neutrinos produced by the gravitational collapse in our Gala xy. The major fraction (similar to 90%) of the gravitational binding energy is radiated in the succeeding similar to 20 s, i.e., over a fairly long ti me interval, as in Nadyozhin calculations (1978). We also calculated the co llapse of stellar core with rapid initial solid-body rotation using the sph erically symmetric approximation with averaging of the centrifugal force ov er the solid angle. Parameters of a rapidly and differentially rotating fin ite-sized neutron star point to the possibility of the stellar core to frag ment in the course of the collapse.