Scientists watched a star explode in real time for the first time ever

Astronomers have watched a giant star blow up in a fiery supernova for the first time ever — and the spectacle was even more explosive than the researchers anticipated.

According to a new research published Jan. 6 in the Astrophysical Journal, scientists began observing the doomed star — a red supergiant called SN 2020tlf and located approximately 120 million light-years from Earth — more than 100 days before its last, cataclysmic collapse. During that time, the researchers witnessed the star erupt with dazzling bursts of light as massive globs of gas exploded from its surface.


A red supergiant star evolving into a Type II supernova, unleashing a powerful explosion of radiation and gas on its final breath before collapsing and exploding. (Photo courtesy of W. M. Keck Observatory/Adam Makarenko)

These pre-supernova fireworks surprised the researchers because earlier observations of red supergiants on the verge of exploding showed no signs of violent emissions, they 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 the popularity of big stars explodes

Red supergiants are the largest stars in the Universe, with radii hundreds to thousands of times the radius of the Sun. (Despite their mass, red supergiants are neither the brightest nor the most massive stars in the universe.)

These massive stars, like our sun, generate energy through nuclear fusion of atoms in their cores. Red supergiants, on the other hand, can produce elements much heavier than the hydrogen and helium that our Sun burns. As supergiants burn heavier and heavier elements, their cores heat up and become more compressed. These stars eventually run out of energy and begin to fuse iron and nickel, collapsing their cores and releasing gaseous atmosphere into space in cataclysmic Type II supernova explosions. Scientists have detected red supergiants before they become supernovae and analyzed the aftermath of these cosmic explosions, but until now have never witnessed the entire process in real time.

The authors of the new study began investigating his SN 2020tlf in the summer of 2020. The star flared up in a dizzying burst of radiation, later interpreted as gas erupting from the surface of the star. Using two of his telescopes in Hawaii, the researchers tracked the glowing star for 130 days.University of Hawaii Astronomical Institute Pan-STARRS1 telescope; WM Keck Observatory on Mauna Kea; Finally, at the end of that hour, the star exploded.

Researchers found evidence of dense clouds of gas surrounding the star at the moment of its explosion. This is likely the same gas the star has been emitting in the last few months. This indicates that the massive explosion began long before the stellar core collapsed in the fall of 2020.

“A dying red supergiant star that produces such a bright emission and then collapses and burns up,” study co-author Rafaela Margutti, an astrophysicist at the University of California, Berkeley, said in a statement. We have never seen any active activity,” he said.

The team’s findings show that red supergiants undergo major changes in their internal structure, leading to chaotic outbursts of gas in the final months before impact.