Computing the collapse of iron-oxygen stellar cores with allowance for theabsorption and emission of electron neutrinos and antineutrinos

The collapse of a 1.4M(.) iron stellar core and a 2M(.) iron-oxygen core is computed by using 1D models. The P proportional to rho(1 + 1/n) polytropes with n = 3 were chosen as the initial models. The equation of state takes into account photon equilibrium radiation, a mixture of Fermi gases of free nucleons and ideal gases of(Fe, He) nuclei in equilibrium relative to nucl ear reactions, and an electron-positron gas. The problem includes the trans fer equations for electron neutrinos and antineutrinos. We allow for the ab sorption and emission of neutrinos and antineutrinos which involve free nuc leons and nuclei. The solution yielded neutrino light curves. The computed light curves exhibit narrow peaks with characteristic widths of approximate to 10 ms. A constraint on the electron-neutrino mass (less than or similar to 4 eV) can thus be placed when short bursts of radiation are recorded du ring observations. Part of the energy of neutrino radiation is absorbed by the stellar core envelope: 3.6 x 10(50) and 1.7 x 10(50) erg for the 1.4M(. ) and 2M(.) models, respectively. We also compute the collapse of a 2M(.) s tellar core with rapid initial rigid rotation with the averaging of the cen trifugal force over the solid angle. The formation of a rapidly rotating ne utron star in the final state points to the possibility of system fragmenta tion during the collapse.