Astronomers Catch Glimpse of What Happens Just Before the Violent Death of a Star

Astronomers have caught a glimpse of the moments just before a star's violent death—and they've observed something that has never been documented before.

We know that when massive stars reach the end of their lifecycle, a cataclysmic explosion known as a supernova occurs.

Now, in a paper published in the journal Nature Astronomy, an international team has observed that supernovae generated by red supergiants—the largest stars in the universe in terms of volume—produce a "flash" before the main explosion that has not been predicted by current models.

The group from the University of Chile (UC), the Millennium Institute of Astrophysics (MAS) and other institutions made the discovery after scanning the sky for 14 nights using the DECam instrument on the Victor Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile.

DECam is a 570-megapixel camera—one of the most powerful that exists—that is capable of digitally capturing the light of more than 100,000 galaxies up to a distance of 8 billion light-years in each exposure.

The group observed the stellar explosions in real time in their initial stages using a unique data analysis technique built on machine learning and astrophysical models. The latest findings shed new light on supernova explosions and the late stages of the stellar lifecycle.

According to the researchers, the "flash" is caused by a collision between the rapidly expanding gas of the supernova and a material of unknown origin that surrounds the star.

"The presence of this material makes it possible to extract part of the enormous energy produced during the explosion and turn it into light that we can detect," Francisco Förster, lead author of the paper from UC and MAS, said in a statement.

The discovery will open up new avenues of research for upcoming large telescopes that are being built in northern Chile, which will make observations of the entire sky every three nights. This will enable scientists to collect more data on supernovae, which will ultimately broaden our understanding of this explosive celestial phenomenon.

Stock image of a supernova explosion. iStock

"This result shows how in the era of Big Data, the use of advanced computing techniques to filter massive data sets delivered by modern instruments such as DECam allow scientific discoveries that would have been impossible in the past," director of Cerro Tololo Steve Heathcote said in the statement.

"The techniques developed at UC will be critical tools to handle the large amount of data that will come from the Large Synoptic Survey Telescope when it starts operations in Chile in 2023," he added.