Core-collapse supernovae are attributed to a sequence of cataclysmic events presumed to follow from the exhaustion of the fusion fuel in the core of a star at least eight times more massive than the Sun: When the outward thermal and radiation pressure from exothermic nuclear fusion no longer balances the gravitational crush of the star’s outer layers, the core suddenly collapses. The rebound from the collapse propels a shock wave outward through the star as a prelude to the eventual ejection of most of the star’s material. Only a remnant neutron star—or a black hole—is left behind. The signature supernova light that first appears about a day later is eventually dominated, after weeks or months, by incandescence of the ejecta heated by the decay of radioactive nickel-56 created in the explosion.
The broad outlines of this scenario are supported by extensive observations of various spectroscopic classes of core-collapse supernovae at...
