Collapse of a low-mass iron stellar core

An implicit method is worked out for calculations of stellar evolution and collapse through static and dynamic stages governed by electron captures on nuclei. The results of calculations are given for a 1.2 M_sun; stellar core prior to neutrino trapping. It is shown that the transition to nuclear statistical equilibrium produces a thermal burst and stellar pulsations of small amplitude. The role in the collapse of the Gamov-Teller resonance of nuclear excitations which changes the rates of beta transitions is investigated.