Astronomers have seen a huge star explode in a fiery supernova for the first time ever. The event was even more spectacular than the scientists had expected.
According to a new study published in the Astrophysical Journal on January 6, scientists began watching SN 2020tlf, a red supergiant 120 million light-years away from Earth, more than 100 days before its last, catastrophic collapse. During this time, the scientists witnessed the star erupting with bright flashes of light and huge balls of gas shooting out of its surface.
These pre-supernova pyrotechnics came as a big surprise, as previous observations of red supergiants about to blow their tops showed no traces of violent emissions, the researchers said.
“This is a breakthrough in our understanding of what massive stars do moments before they die,” lead study author Wynn Jacobson-Galán, a research fellow at the University of California, Berkeley said in a statement. “For the first time, we watched a red supergiant star explode!”
When big stars go boom
In terms of volume, red supergiants are the largest stars in the universe, measuring hundreds or even thousands of times the radius of the sun. (Despite their bulk, red supergiants are not the brightest or most massive stars in the universe.)
Atoms in the cores of these huge stars fuse together to make energy, just like our sun does. On the other hand, red supergiants can make things that are much heavier than the hydrogen and helium that our sun burns. As supergiants burn heavier elements, their cores get hotter and more compact. When these stars start fusing iron and nickel, their cores collapse, and they send their gassy outer atmospheres into space in a type II supernova explosion, they run out of energy.
Scientists have observed red supergiants before they go supernova and studied the aftermath of these cosmic explosions, but they have never witnessed the entire process in real time until now.
The new study’s authors began observing SN 2020tlf in the summer of 2020, when the star flickered with bright flashes of radiation, which they later interpreted as gas exploding off the star’s surface. The researchers tracked the cranky star for 130 days using two telescopes in Hawaii: the University of Hawaii Institute for Astronomy Pan-STARRS1 telescope and the W. M. Keck Observatory on Mauna Kea. Finally, at the end of that time, the star exploded.
Researchers found evidence that a dense cloud of gas was surrounding the star at the time of its explosion. This cloud of gas was probably the same gas that the star had been giving off in the months before its explosion. This shows that huge explosions started long before the core of the star broke apart in the fall of 2020.
“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,” study co-author Raffaella Margutti, an astrophysicist at UC Berkeley, said in the statement.
These observations suggest that red supergiants undergo significant changes in their internal structures, resulting in chaotic explosions of gas in their final months before collapsing, the team concluded.
READ MORE: Here’s What the Supergiant Star Betelgeuse Will Look Like When It Goes Supernova (video)
