This huge monster, whose mass is 20 million times that of our sun, is unleashed in the outer vacuum and collides with the clouds of gas that are in its path.

Given the disproportionate forces involved, this gas then turns into a trail of stars, which have been spotted by NASA's Hubble Space Telescope.

"We think we see a wake behind the black hole where gas cools and can form stars," Pieter van Dokkum, a scientist at Yale University, said in a statement. "What we see are the after-effects. Like the wake of a ship, we see the wake of the black hole."

The researchers believe that the gas is likely warmed by the collision with the black hole, then cools after it passes, giving rise to the stars seen on its path.

"The gas in front of him is hit by the supersonic impact, at very high speed, of the black hole," van Dokkum said.

Scientists believe that the celestial beast is the result of a colossal ménage à trois interstellar.

According to their theory, two galaxies probably merged about 50 million years ago, causing two supermassive black holes to rotate around each other.

Discovered by accident

But a third galaxy, with its own black hole, would then collide with this set. Enough to create an unstable and chaotic trio, which ended up ejecting one of the black holes at a phenomenal speed: the monster spotted by Hubble could cover the distance between the Earth and the Moon in just 14 minutes.

For us poor humans, there is no risk of being swallowed by this huge celestial object, according to the researchers responsible for this discovery. All this happened far away in space and a long time ago, when the universe was half its current age.

We see this phenomenon today because the light took a long time to reach us.

The discovery was made by accident, according to van Dokkum.

Using the Hubble telescope, the scientist "noticed (...) a little trail" of stars, "quite amazing, very, very bright and very unusual". "It wasn't like anything we'd seen before."

Never observed before, this kind of black hole may not be alone in the universe, according to NASA.

The new Nancy Grace Roman telescope, scheduled for launch this decade, is expected to observe space much more widely, and could spot other star trails signaling the presence of one of these colossi.

© 2023 AFP