It is the first time a red supergiant has gone supernova
It’s still rare to see a star in the process of going supernova, despite the fact that there are so many of them in the sky. Astronomers have now captured a red supergiant before, during, and after a supernova explosion for the first time, allowing them to gain critical new insights into these events.
Lead author Wynn Jacobson-Galán declared, “This is a breakthrough in our understanding of what massive stars do moments before they die” (UC Berkeley). “In an ordinary Type II supernova, direct detection of pre-supernova activity has never been observed. We witnessed a red supergiant star exploding for the first time!”
The massive amount of light emitted by the dying red supergiant star was detected by the Pan-STARRS telescope in Maui, Hawaii, in the summer of 2020. When it went supernova later that fall, the Keck Observatory’s Low-Resolution Imaging Spectrometer in Hawai’i was able to capture the powerful flash (LRIS). They also got the first look at the supernova’s spectrum, which they dubbed SN 2020tlf.
Preliminary evidence suggests massive amounts of dense circumstellar material were likely ejected from the star prior to its explosion. The new data suggests that some red giants may undergo significant structural changes before exploding, which is in line with previous observations showing that they were relatively calm before going supernova. This could lead to a flurry of gas ejections just before the building collapses.
About 120 million light-years from Earth, the NGC 5731 galaxy houses SN 2020tlf, a star 10 times more massive than the Sun. When a star runs out of fuel and collapses due to its own gravity, a massive carbon fusion explosion occurs, resulting in a supernova. In order for this to occur, they must be sufficiently massive (8 to 15 solar masses), or else they will eventually collapse into a white dwarf star, just like our Sun. A black hole could form if they were any larger than that.
Using this discovery, researchers will be able to search red supergiant stars for luminous radiation that could indicate the presence of another supernova. As more events like SN 2020tlf are discovered, they will “dramatically impact how we define the final months of stellar evolution,” said Jacobson-Galán.