What does a dying star look like? Astronomers have suspected that they might become red supergiants and explode. But no one has captured this phenomenon. Now, using ground and space-based telescopes, astronomers have recorded how a star about 120 million light-years from Earth collapsed and exploded. The star was located in the outer reaches of the galaxy NGC 5731.
“It’s like watching a ticking time bomb,” said senior author Raffaella Margutti, associate professor of astronomy and of physics at UC Berkeley in a release. “We’ve never confirmed such violent activity in a dying red supergiant star, where we see it produce such a luminous emission, then collapse and combust, until now.”
The discovery was published in The Astrophysical Journal. The energetic explosion was named supernova 2020tlf, or SN 2020tlf.
Study lead author Wynn Jacobson-Galán said, “Detecting more events like SN 2020tlf will dramatically impact how we define the final months of stellar evolution, uniting observers and theorists in the quest to solve the mystery on how massive stars spend the final moments of their lives…I am most excited by all of the new ‘unknowns’ that have been unlocked by this discovery.”
The increase in brightness in the final months suggests that the supergiant underwent changes in its internal structure that resulted in the ejection of gas.
The researchers suggest that before the ultimate explosion, the gaseous material it expelled could have come from nuclear reactions inside the star. Previously, models of such nuclear reactions have suggested that sudden flashes of neon and oxygen fusion could generate gravitational waves that blow off some of the outer regions of the star.