Daniel Kasen, an assistant professor of astronomy and physics at UC Berkeley and a faculty scientist in Berkeley Lab‘s Nuclear Science Division, said: ‘It only takes a few seconds for the shock wave to tear apart the star, but the debris heated in the explosion will continue to glow for several hours.

‘The bigger the star, the brighter this afterglow. Because we caught this supernova so early, and with such sensitive observations, we were able to directly constrain the size of the progenitor.’