For the first time, astronomers witnessed the explosion of a massive star in a fiery supernova, and the spectacle was even more spectacular than scientists had predicted.

According to a recent study published January 6 in the Astrophysical Journal, scientists began observing the doomed star more than 100 days before its latest violent collapse. The star is a red supergiant called SN 2020tlf and is located about 120 million light years from Earth.

Scientists witnessed the star’s eruption during that lead-up period, and saw large balls of gas erupt from the star’s surface in bright flashes of light.

An artist’s rendering of a red supergiant star that is about to explode as a type II supernova, releasing a powerful burst of gas and radiation as it approaches collapse. (Photo courtesy of Adam Makarenko and the WM Keck Observatory.)

The researchers noted that previous investigations of exploding red supergiants had revealed no signs of strong emissions, so these pre-supernova fireworks came as a big surprise.

According to a statement made by the study’s lead author, Wynn Jacobson-Galán, a researcher at the University of California, Berkeley, “this is a major advance in our understanding of what massive stars do moments before they die.” “WE SAW A RED SUPERGIANT STAR EXPLODE FOR THE FIRST TIME!”

When the big stars explode

Red supergiants, measuring hundreds or even more than a thousand times the radius of the Sun, are the largest stars in the universe in terms of volume. (Despite their volume, red supergiants are not the most massive or brightest stars in the universe.)

These huge stars produce energy through the nuclear fusion of atoms at their centers, just as our sun does. However, red supergiants can create elements much heavier than the hydrogen and helium that our sun consumes due to their immense size. The cores of supergiants become hotter and more pressurized as they burn larger and larger components. Eventually, these stars run out of energy, their cores collapse, and they release their outer gaseous atmospheres into space in a cataclysmic type II supernova explosion, which occurs when they begin to fuse iron and nickel.

Although they have studied the consequences of these cosmic explosions and detected red supergiants before they become supernovae, scientists have never before witnessed the entire process in real time.

The star flickered with dazzling bursts of radiation in the summer of 2020, which the authors of the new study eventually deduced were gas erupting from the star’s surface. That’s when they started observing SN 2020tlf. Researchers observed the irritable star for 130 days using two telescopes in Hawaii: the WM Keck Observatory on Mauna Kea and the Pan-STARRS1 telescope at the University of Hawaii Institute for Astronomy. Finally, the star exploded at the end of that time.

At the time of the explosion, scientists observed evidence of a dense cloud of gas surrounding the star; They concluded that this gas was probably the same gas that the star had been exhaling in the previous months. This implies that the star’s catastrophic explosions began long before its core collapsed in autumn 2020.

“UP TO THIS POINT, WE HAVE NEVER CONFIRMED SUCH VIOLENT ACTIVITY IN A BURNING RED SUPERGIANT STAR WHERE WE SEE IT PRODUCE A LUMINOUS EMISSION, THEN COLLAPSE AND COMBUST,” UC Berkeley astrophysicist and study co-author Raffella Montaguti said in the statement.

The team concluded that these data imply that red supergiants undergo major structural changes that cause chaotic gas explosions in the final months before they collapse.