It was a core collapse supernova. “For the first time we saw a red supergiant explosion! The activity of such a giant star has never been followed before it exploded in a Type II supernova,” says Jacobson-Gallen. The supergiant was about 5000 Kelvin hot before its end and contained 1,500 times the radius of our Sun. It was also ten times more massive than our central star.

Astonishingly, the dying star was still highly active before its termination, releasing enormous amounts of radiation and matter. Jacobson-Gallon and Company wrote that this was the first type II supernova for which such a high level of activity was observed. Otherwise, the moments before the respective supernova were very quiet. At least some supergiants are behaving differently from what was previously observed.

Rapid changes in the star’s internal structure, which led to a sudden supply of energy to the shell, are probably to blame. This was followed by an increase in the production of stellar material, which was eventually observed. However, how the energy was supplied is not clear. Gravitational waves from the fusion of neon and oxygen or a nuclear flash from the combustion of silicon can be considered. But these are still hypotheses, write astronomers.