What is a supernova?
When the fusion reactions in a massive star end, it collapses and throws off its outer layers in a giant explosion. In just a few seconds, huge amounts of energy – about 100 times the energy generated by our sun during its lifetime – are released. Gravitation compresses the stellar core, producing a neutron star or – if the star is sufficiently massive – a black hole. Protons in the stellar core are transformed into neutrons, a process which also generates neutrinos. Some of these were detected by Kamiokande.