A “supermassive” black hole is tearing through space at full speed, leaving behind a trail of stars 200,000 light years long, according to a groundbreaking discovery announced by NASA on Friday.
The huge monster, with a mass 20 million times that of our sun, rages through the interstellar void and smashes into clouds of gas in its path. Given the inordinately powerful forces at play, this gas then turns into a trail of stars, spotted by NASA’s Hubble Space Telescope.
“We think we’re seeing a wake behind the black hole where the gas cools and is able to form stars. So we’re looking at star formation trailing the black hole,” Pieter van Dokkum, a scientist at Yale University, explained in a statement.
'It didn't look like anything seen before'
“What we are seeing is the aftermath. Like the wake behind a ship, we’re seeing the wake behind the black hole,” he added. “It didn’t look like anything we’ve seen before.”
Researchers believe the gas is likely heated by the collision with the black hole and then cools after it passes, giving rise to the stars seen in its path.
“Gas in front of it gets shocked because of this supersonic, very-high-velocity impact of the black hole moving through the gas,” said van Dokkum. “How it works exactly is not really known.”
...the result of a colossal interstellar ménage à trois'
Scientists believe the celestial beast is the result of a colossal interstellar ménage à trois. According to their theory, two galaxies probably merged about 50 million years ago, causing two supermassive black holes to orbit each other.
But a third galaxy, with its own black hole, would then have collided with that ensemble. This created an unstable, chaotic trio, which eventually ejected one of the black holes at 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 up by this huge celestial object, according to the researchers responsible for this discovery. It all happened far out in space and a very 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.
Future telescope could spot more runaway black holes
This discovery was made by accident, van Dokkum said.
Using the Hubble telescope, the scientist “noticed (…) a small trail” of stars, “quite amazing, very, very bright and very unusual”.
Never before observed, this kind of black hole may not be alone in the universe, according to NASA.
The new Nancy Grace Roman telescope, scheduled to be launched later this decade, is expected to observe space much more widely, and could spot other star trails signalling the presence of one of these behemoths.