Astronomers witnessed a red supergiant star in its final days and its massive explosion as it died and turned into a supernova, the first time that instance has ever been observed.
The star was first discovered in summer 2020 by a team of researchers at Northwestern University and the University of California, Berkeley using the University of Hawaii’s Pan-STARRS telescope at the peak of the Haleakalā volcano in Maui.
A few months later, the automated telescope caught the the star’s death. The team’s finding were published in the Astrophysical Journal on Jan. 6.
“The death of a of a massive star like this, it’s very dramatic and very violent,” Wynn Jacobson-Galán, astrophysicist at UC Berkeley and lead author of the study told USA TODAY. “We’ve never really seen anything like this.”
Supernovas are the biggest explosions ever witnessed by humans and typically happen with giants stars 8-to-12 times bigger than the sun, according to NASA. While they have been seen by humans, they’ve only been detected after the explosion occurred, when gas and other debris gets shot out into space. That debris can then form new stars and produce elements found on Earth.
Jacobson-Galán said the star was in a very distant galaxy, roughly 120 million light years away. After the team first saw it, they got to watch it progressively get brighter while emitting gas before it blew and lit up space. The massive explosion all happened in less than a minute.
“Supernovae are really, really impressive because they come from a single star that can then produce an explosion and light and photons that are bright enough to outshine the entire galaxy that they originated in,” he said.
Even though the team saw the end of the star’s life unfold, they were still unsure what exactly they saw because it had never been observed before. After analyzing the data from when the star was intact and comparing it to the supernova, they realized they were in fact connected, giving them a sense of “delayed gratification.”
Jacobson-Galán said modern technology played a huge role because observing stars in their final days was never considered. Supernovas are always spotted because of their brightness, but the telescopes used were able to spot the star just before it died.
This observation also changes the way astronomers understand the life cycle of stars, specifically a red supergiant, Jacobson-Galán said. It had long been thought the stars would just quietly collapse into a supernova, not get brighter and intense. The next step is figuring out if this happens to all red supergiant stars, or just some, as well as what exactly is happening in the final stages of the star’s life.
“It’s a really powerful discovery for us to understand what massive stars are doing before they explode, because clearly this particular star was undergoing a lot of dramatic changes,” Jacobson-Galán said. “The future of this is actually really exciting.”