Scientists Watched the Violent Death of a Red Supergiant Star in Real-Time

"This is a breakthrough in our understanding of what massive stars do moments before they die," said lead study author Wynn Jacobson-Galán, a National Science Foundation Graduate Research Fellow at the University of California, Berkeley. "Direct detection of pre-supernova activity in a red supergiant star has never been observed before in an ordinary type II supernova. For the first time, we watched a red supergiant star explode."

Red stars are the largest star type in the universe in terms of volume, though they aren't the brightest or most massive. Before the new observation, it was believed that red supergiant stars were relatively quiet before the supernova explosion that signaled the end of their lifespan. However, the new findings dramatically suggested otherwise.

"It's like watching a ticking time bomb," said senior study author Raffaella Margutti, an associate professor of astronomy and astrophysics at UC Berkeley. "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."

Astronomers are keen to seek out more supernova observations

Astronomers first discovered signs of unusual activity 130 days before the star in NGC 5731 went supernova. The University of Hawaii Institute for Astronomy Pan-STARRS telescope on Maui's Haleakalā detected bright radiation in the summer of 2020.

Then, only a few months later, they witnessed the supernova, which was named SN 2020tlf. Next, the researchers say they hope to detect more events like SN 2020tlf, in a bid to better understand the evolution and eventual demise of stars.

In 2019, the red supergiant star Betelgeuse, located within the Milky Way, dimmed to its lowest brightness level in years prompting some astronomers to believe it might be about to go supernova. However, unlike the star in NGC 5731, Betelgeuse remains intact.