An early outburst foreshadows a star's death

An early outburst foreshadows a star's death

Scientists have discovered the first early warning sign of a common supernova.

A star's death is generally unexpected. However, an early warning of a star's impending doom provides insight into what occurs before some stellar explosions.

A star brightened as a last hurrah before exploding, implying that it expelled part of its outer layers into space. Researchers reveal in the Astrophysical Journal on January 1 that they have discovered a pre-explosion outburst from a common form of exploding star or supernova.  

Scientists have previously observed signs of unique supernova kinds. "What's nice about this one is it's a much more conventional, vanilla... supernova that's showing this eruption before the explosion," says Caltech astronomer Mansi Kasliwal, who was not involved in the study.

Scientists discovered the explosion of a star nearly 10 times the mass of the sun on September 16, 2020, some 120 million light-years away. Thankfully, telescopes that sweep a large section of the sky regularly as part of the Young Supernova Experiment had been watching the star long before it exploded. The star brightened about 130 days before the explosion, indicating the start of a pre-explosion eruption, according to the researchers.

The last explosion was a type 2 supernova, a frequent sort of stellar detonation that occurs when the core of an old star collapses. Because the early eruptions are so feeble, no precursors to such events were likely witnessed before. Scientists have observations of the star sensitive enough to pick up the comparatively faint outburst for this supernova.

Before the explosion, there was The stars slough off layers before dying, according to studies of such supernovas. Astronomers discovered evidence of a supernova's shock wave crashing into debris ejected by the star in 2021 (SN: 11/2/21). The current investigation also discovered a similar trace of discarded star debris.

Scientists are baffled as to what triggers such early outbursts. They could be the result of activities taking place deep within a star, such as a star burning various types of fuel as it approaches death. If more of these occurrences are discovered, astronomers may be able to forecast which stars will explode and when.

According to research coauthor Raffaella Margutti, an astrophysicist at the University of California, Berkeley, precursor eruptions are a warning that stars are experiencing inner turmoil before bursting. "The most important message we're getting from the universe is that these stars are fully aware that the end is near."