What primarily powers a Type II core-collapse explosion?
A flood of neutrinos converted from mass.
The core-collapse supernova, characteristic of massive stars exceeding eight solar masses, achieves its incredible power chiefly through the release of neutrinos during the final seconds of core implosion. As gravity crushes the iron core until protons and electrons merge into neutrons, an enormous amount of energy is converted into these nearly massless particles. Estimates suggest that about $10^{46}$ joules, equivalent to roughly $10\%$ of the star's entire rest mass, are carried away by this neutrino flood in just a few seconds. While the visible explosion, powered by the rebound shockwave and subsequent heating by these neutrinos, is bright, this neutrino emission is nearly two orders of magnitude greater than the total energy observed as visible light and kinetic energy combined. Therefore, the event is fundamentally powered by particle physics—the neutrino burst—rather than sustained thermonuclear burning or kinetic energy alone.
