The giant star disappeared, something terrible took its place

(NLDO) - A variable star has broken conventional cosmological theory right before the eyes of Earthlings.

According to Science Alert, the results of monitoring a variable star named M31-2014-DS1 in the Andromeda galaxy, a giant neighbor of the Milky Way, have completely confused scientists.

Astronomers noticed M31-2014-DS1 brightening in the mid-infrared (MIR) in 2014.

For the next 1,000 days, its brightness remained constant. But for the next 1,000 days between 2016 and 2019, it dimmed considerably.

A giant star inside the Andromeda galaxy may have suddenly turned into a black hole - Illustration AI: ANH THU

It is a variable star, which means its brightness changes over time, but that cannot explain the fluctuations.

In 2023, it became even more strange when it was undetectable in deep and close optical imaging observations. It appeared to be dead, but not in the usual way.

Widely accepted theories suggest that a massive star like M31-2014-DS1 would undergo a powerful supernova explosion — causing it to flash suddenly — before collapsing into a compact neutron star.

This neutron star also has the potential to explode again at the end of its life and create a stellar-mass black hole.

M31-2014-DS1 was born with an initial mass of about 20 solar masses and reached its final nuclear burning stage with a mass of about 6.7 solar masses.

So if it exploded, scientists would have to see the explosion very clearly.

New observations show that where it once resided, something was surrounded by a newly erupted dust shell, similar to what happens after a supernova.

So what can keep a star from exploding into a supernova, even if it has the right mass to explode?

A supernova is an event in which the density inside the core collapses so much that electrons are forced to combine with protons, creating both neutrons and neutrinos, the "demon particles".

This process is called neutronization and produces a powerful explosion called a neutrino shock.

Neutrinos are called "ghost particles" because they are electrically neutral particles that rarely interact with anything around them.

But in the dense core of a star, the density of neutrinos is so great that some of them deposit their own energy into the surrounding stellar matter, heating the matter, creating shock waves.

The neutrino shocks always stop, but sometimes they revive, possibly because the neutrino emission itself may have provided the energy. When they revive, they cause an explosion and push the outer layers of the supernova off.

In M31-2014-DS1, the neutrino shock was not revived and it became a failed supernova.

"This implies that most of the star's matter collapsed into the core, exceeding the maximum mass of a neutron star and forming a black hole," explained Dr. Kishalay De from the Kavli Institute for Astrophysics and Space Research at the Massachusetts Institute of Technology (MIT - USA).

It is estimated that up to 98% of the star's mass collapsed, and what took its place was a black hole 6.5 times the mass of the Sun.

This discovery proves the hypothesis that some giant stars can skip stages and directly transform into black holes, something that was suspected with N6946-BH1, a superluminous star that suddenly disappeared in 2015.

Source: https://nld.com.vn/ngoi-sao-khong-lo-bien-mat-mot-thu-khung-khiep-the-cho-196241112112259011.htm