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Supernova Type II

Stars with at least nine solar masses of material evolve in a complex fashion. The core collapses in on itself with velocities reaching 70,000 km/s (0.23c) resulting in a rapid increase in temperature and density. The energy loss processes operating in the core cease to be in equilibrium. In a typical Type II supernova the newly formed neutron core has an initial temperature of about 100 billion kelvin (100 GK), 6000 times the temperature of the sun's core. About 10^46 joules of gravitational energy - approximately 10% of the star's rest mass - is converted into a ten-second burst of neutrinos, which is the main output of the event. These carry away energy from the core and accelerate the collapse, while some neutrinos are absorbed by the star's outer layers and provide energy to the supernova explosion. The inner core eventually reaches typically 30 km diameter, and a density comparable to that of an atomic nucleus, and further collapse is abruptly stopped by strong force interactions and by degeneracy pressure of neutrons.