California

Stars have a life and death cycle. Those that are about eight times more massive than the Sun explode as supernovae at the end of their lives. They leave behind a black hole or a neutron star which are extremely bright, even more than their host galaxies. This can last for months.

Advertisment

However, astronomers have discovered a star that seemingly went straight to becoming a black hole without any explosion taking place. The outward force of fusion and the inward force of a star's own gravity is what keeps them going. When the hydrogen exhausts, the fusion weakens.

The star soon collapses in on itself, resulting in a supernova explosion followed by a black hole or a neutron star. However, new research indicates that some of them do not witness any explosion. 

This is what happened with one massive, hydrogen-depleted supergiant star in the Andromeda galaxy (M31) that did not detonate. 

Advertisment

The cosmic event is mentioned in the research titled, "The disappearance of a massive star marking the birth of a black hole in M31." Kishalay De, a postdoctoral scholar at the Kavli Institute for Astrophysics and Space Research at MIT, is its lead author. 

Such supernovae are called core-collapse supernovae and are extremely rare. One of them occurs approximately every hundred years in the Milky Way.

Also Read: Another 'devil' comet? Volcanic icy body witnesses multiple violent explosions

Advertisment

Supernovae are still a mystery

Scientists believe that the latest finding shows that there is a lot humans still don't know about supernovae. 

Named M31-2014-DS1, it was first seen becoming extremely bright in mid-infrared (MIR) in 2014. It stayed in one stage of luminosity for 1,000 days. Between 2016 and 2019 for another 1,000 days, it faded dramatically.

Then in 2023, astronomers tried to view it in deep optical and near-IR (NIR) imaging observations, but it was undetectable.

As per the researchers, the star initially had a mass of about 20 stellar masses and reached its terminal nuclear-burning phase with about 6.7 stellar masses. A recently ejected dust shell, left behind by a supernova explosion, surrounds it, although there is no evidence of an optical outburst.

"The dramatic and sustained fading of M31-2014-DS1 is exceptional in the landscape of variability in massive, evolved stars," the authors write.

"The sudden decline of luminosity in M31-2014-DS1 points to the cessation of nuclear burning together with a subsequent shock that fails to overcome the infalling material."

In 2009, astronomers discovered a failed supernova, the only other one confirmed ever. The star was a supergiant red star in the NGC 6946, a "Fireworks Galaxy."