Scientists Observe a Red Supergiant Going Supernova for the First Time

The massive number of stars in the sky, spotting one in the throes of a supernova, is still a sporadic event. Astronomers have captured a red Supergiant before, during, and after a supernova explosion for the first time, gathering crucial new information about these dramatic events.Wynn Jacobson-Galán, the study’s lead author, said that this is a breakthrough in our understanding of what massive stars do moments before they die.

In an ordinary Type II supernova, the direct detection of pre-supernova activity in a red Supergiant star has never been observed before. For the first time, we watched a red Supergiant star explode.Using the Pan-STARRS telescope in Maui, Hawai’i, scientists detected the doomed red Supergiant star in the summer of 2020, thanks to its emitting a tremendous amount of light. In the fall, when it went supernova, the team captured the powerful flash using the Hawai’i-based Keck Observatory’s Low-Resolution Imaging Spectrometer. They also captured the very first supernova spectrum, known as SN 2020tlf.

The observations revealed that the star likely ejected massive amounts of dense circumstellar material just ahead of the explosion. Observations showed that red giants were relatively calm before going supernova, so the new data suggests that some may change their internal structure significantly before exploding. That could then result in tumultuous gas ejections moments before the collapse.

SN 2020tlf is located in the NGC 5731 galaxy, about 120 million light-years from Earth, and was about ten times more massive than the Sun. Stars go supernova when they run out of fuel and collapse on their gravity, fueling an enormous carbon fusion explosion. For that to happen, they must be large enough, or they’ll simply collapse into a white dwarf star like our Sun eventually will. Any more significant than that, and they could collapse into a black hole. The discovery will now allow scientists to survey red Supergiant stars looking for similar types of luminous radiation that could signal another supernova.