Yingzhen Cui

70 days. That's exactly how long the plateau, the steady glow after the blast, lasted for supernova SN 2018gj. Usually, these plateaus stretch a hundred days or more. This short plateau was the first crack in the star's mask. Images from the Hubble Space Telescope pinpointed the progenitor: a red supergiant. Enormous. Cold.

Massive stars end their lives in a grand explosion — a supernova. Their cores collapse into a neutron star (a super-dense ball where a teaspoon of matter weighs a billion tons) or a black hole. For a long time, the most common type of such outbursts was thought to be the domain of solitary stars. However, supernova SN 2018gj broke the rule.