A Hubble Space Telescope (HST) image of NGC 1850. Credit: ESA, NASA and Martino Romaniello (European Southern Observatory, Germany).

It is a cluster of thousands of stars located about 160,000 light-years away in the Large Magellanic Cloud, a neighboring galaxy of the Milky Way.

It is the first time that this detection method has been used to reveal the presence of a black hole outside our galaxy. The method could be key in revealing the presence of hidden black holes in the Milky Way and nearby galaxies and in helping to shed light on how these mysterious objects form and evolve.

It is the first time that this detection method has been used to reveal the presence of a black hole outside our galaxy. The method could be key in revealing the presence of hidden black holes in the Milky Way and nearby galaxies and in helping to shed light on how these mysterious objects form and evolve.

The newly discovered black hole was detected in NGC 1850, a cluster of thousands of stars located some 160,000 light-years away in the Large Magellanic Cloud, a neighboring galaxy to the Milky Wa

“We observe each and every one of the stars in that cluster and, like Sherlock Holmes when he followed the missteps of a criminal gang with his magnifying glass, we try to find some evidence of the presence of black holes, although without seeing them directly”, said in a statement Sara Saracino, from the Astrophysical Research Institute of the John Moores University of Liverpool (United Kingdom), who led this research, accepted for publication in the Monthly Notices of the Royal Astronomical Society magazine. “The result we show would represent only one of the wanted criminals, but when you find one, you are well on your way to discovering many others in different clusters.”

This first “criminal” the team tracked down turned out to be about 11 times more massive than our Sun. The evidence that put the team on the trail of this black hole was its gravitational influence on the orbiting five-solar-mass star. The astronomical community had previously detected such small “stellar mass” black holes in other galaxies by capturing the glow of X-rays emitted when they swallow matter, or from the gravitational waves generated when black holes collide with each other or with neutron stars.

However, most stellar-mass black holes do not give away their presence through X-rays or gravitational waves. “The presence of the vast majority can only be dynamically revealed,” said Stefan Dreizler, a member of the team based at the University of Göttingen (Germany). “When a black hole forms a system with a star, it will affect the movement of the star in a subtle but detectable way, so with sophisticated instruments, we will be able to find them.”