An "invisible monster" in the form of a supermassive black hole is tearing through intergalactic space, leaving behind a 200,000-light-year-long "contrail" of new stars in its wake, according to NASA, citing a team's discovery of the aftermath of the runaway black hole that was captured through images from the Hubble Space Telescope.
The black hole is "barreling through intergalactic space so fast that if it were in our solar system, it could travel from Earth to the moon in 14 minutes," NASA said in a press release.
"We think we're seeing a wake behind the black hole where the gas cools and can form stars. So, we're looking at star formation trailing the black hole," Pieter van Dokkum of Yale University explained. "What we're seeing is the aftermath. Like the wake behind a ship, we're seeing the wake behind the black hole."
The trail of new stars is already twice the diameter of the Milky Way, and the runaway black hole, rather than consuming the stars ahead of it, is pushing into the gas that's in front of it to create the new star formation, and it's "streaking too fast to take time for a snack."
The black hole has formed at the end of a column of its parent galaxy and features a "remarkably bright knot" of ionized oxygen at the outermost tip.
"Gas in front of it gets shocked because of this supersonic, very high-velocity impact of the black hole moving through the gas. How it works exactly is not really known," van Dokkum said.
The theory is that gas is either being shocked and heated from the movements of the black hole or that radiation is being caused by an accretion disk around the black hole.
In any case, NASA said the Hubble Space Telescope accidentally captured the rare sighting, and that nothing like the massive star-creating black hole has been seen before.
Van Dokkum said his team was looking for globular star clusters in a nearby dwarf galaxy when he observed the black hole, and it was "pure serendipity that we stumbled across it."
The trail of stars that's being created is "quite astonishing, very, very bright and very unusual," he added.
"I was just scanning through the Hubble image, and then I noticed that we have a little streak," van Dokkum explained. "I immediately thought, Oh, a cosmic ray [is] hitting the camera detector and causing a linear imaging artifact. When we eliminated cosmic rays we realized it was still there. It didn't look like anything we've seen before."
He and the team determined what was going on through the use of spectroscopy with the W. M. Keck Observatories in Hawaii and concluded they were seeing a trail that the black hole was causing.
Van Dokkum's research paper was published Wednesday in The Astrophysical Journal Letters.
The black hole is estimated as weighing as much as 20 million suns, and was likely caused "by a rare, bizarre game of galactic billiards among three massive black holes."
The astronomers think the black hole was set free when two galaxies merged about 50 million years ago, bringing together two supermassive black holes at their centers. After that, a third galaxy brought another black hole, and the three combined to make the "chaotic and unstable configuration."