A star in Andromeda died a silent death, creating a cosmic mystery

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

However, astronomers have discovered a star that apparently went straight into a black hole without an explosion. It is the outer force of fusion and the inner force of a star’s own gravity that keeps them moving. When the hydrogen is depleted, the fusion weakens.

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

This is what happened to a massive, hydrogen-poor supergiant star in the Andromeda Galaxy (M31) that failed to explode.

The cosmic event is mentioned in the study titled: “The disappearance of a massive star that marks the birth of a black hole in M31.” Kishalay De, a postdoctoral researcher at the Kavli Institute for Astrophysics and Space Research at MIT, is the 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.

Scientists believe the latest finding shows that there are still many people who don’t know anything about supernovae.

Named M31-2014-DS1, it was first seen in 2014 becoming extremely bright in the mid-infrared (MIR). It remained in one stage of brightness for 1000 days. Between 2016 and 2019, it faded dramatically for another thousand days.

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

According to the researchers, the star initially had a mass of about 20 stellar masses and reached its terminal nuclear combustion phase at about 6.7 stellar masses. Surrounding it is a recently ejected dust envelope, left behind by a supernova explosion, although there is no evidence of an optical burst.

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

“The sudden decrease in brightness in M31-2014-DS1 indicates a cessation of nuclear combustion, along with a subsequent shock that fails to overcome the infalling material.”

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