A black hole discovered near the Earth: it broke all records

What can be dangerous about such dormant regions of space-time

Just 1924 light years from the solar system, in the constellation Aquila, astronomers discovered a black hole. The object is the most massive stellar-mass black hole ever seen in the Milky Way, exceeding 33 times the mass of the Sun.

Photo: Wikipedia.org.

The new black hole has become the second one, located closest to Earth. The only reason it is visible is because it is in a double orbit with a companion star whose motion cannot be explained in any other way.

To be clear, BH3 (the scientific name for a black hole) poses absolutely no threat. Its gravitational field is no stronger than that of a star of equivalent mass. But as a third dormant black hole has been discovered, according to data from the Gaia optical telescope, scientists are wondering how many more such regions of celestial space exist, moving undetected.

“No one expected to find a high-mass black hole nearby that had gone undetected until now,” says astronomer Pasquale Panuzzo of the Center National de la Recherche Scientifique (CNRS) in France. He adds that “such a discovery can only be made once in your research life.”

Let's be clear: black holes generally fall into different categories based on mass. There are supermassive galaxies that can be millions or billions times the mass of the Sun — they are usually found at the centers of galaxies, and experts don't know exactly how they form. Those holes that have lower stellar mass are formed by the disintegration of stellar cores when massive stars go supernova. They may be about 65 times the mass of the Sun, although larger ones may form through mergers.

The number of stellar-mass black holes in the Milky Way is estimated to be as high as 100 million, but they are not easy to detect , since they are not known to emit any light.

“Sometimes we may notice a flare from one of them if it absorbs some material from a passing star or binary companion star, as this process produces a lot of heat. Otherwise, they simply remain invisible. So far, we have discovered only about 20, and there are several more candidates,” the astronomers explain.

There are several ways to detect dormant stellar-mass black holes, and one of them involves not the black hole itself, but any stars in satellite orbits close enough to be gravitationally bound to the black hole, but not close enough to be consumed by it. These stars will move strangely through space, describing an orbit that we cannot see.

The Gaia optical telescope, orbiting the Sun in the same orbit as Earth, has been operating since 2013. It maps the three-dimensional positions and movements of stars in the Milky Way with the highest accuracy to date. The more time he spends observing stars, the more accurate his measurements become.

The fourth release of Gaia data is not expected until late 2025, but the discovery of BH3, as astronomers checked the data, was too exciting to sit back hands.

“We took the extraordinary step of publishing this paper, based on preliminary data, ahead of the upcoming release of Gaia, due to the unique nature of the discovery,” said astronomer Elisabetta Caffau of CNRS. She continued: “What we know about this system is that the two objects are separated by about 16 times the distance between Earth and the Sun, and orbit each other every 11.6 years. The mass of the black hole is about 32.7 solar masses.”