A massive black hole has been spotted less than 2,000 light-years from Earth

Astronomers have discovered the largest known stellar black hole in the Milky Way Galaxy after observing an unusual wobble in space.

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The so-called “sleeping giant”, called Gaia BH3, has a mass equivalent to about 33 times that of our Sun, and is located 1,926 light-years away in the constellation Aquila, making it the second closest known black hole to Earth. . The closest black hole is Gaia BH1, which is located about 1,500 light-years away and has a mass of approximately 10 times the mass of our Sun.

Astronomers discovered the black hole while combing through observations taken by the European Space Agency's Gaia space telescope in order to release upcoming data to the scientific community. The researchers didn't expect to find anything, but a strange motion — caused by Gaia BH3's gravitational influence on a nearby companion — caught their attention.

Many “dormant” black holes do not have a companion close enough to feed on, so they are difficult to detect and do not generate any light. But other stellar black holes pull material from companion stars, and this exchange of matter releases bright X-rays that can be observed with telescopes.

The wobbling motion of an ancient giant star in the constellation Aquila revealed that it was in an orbital dance with a dormant black hole, the third dormant black hole observed by Gaia.

The researchers used the European Southern Observatory's Very Large Telescope in the Atacama Desert in Chile and other ground-based observatories to confirm the mass of Gaia BH3, and their study also provided new clues about how these massive black holes appear. The results appeared Tuesday in the journal Astronomy and astrophysics.

“No one would have expected to find a high-mass black hole lurking nearby, and it has not yet been discovered,” said lead study author Pasquale Panozzo, an astronomer at the Paris Observatory, part of the French National Center for Scientific Research and a member of the Gaia collaboration. In the current situation. “This is the kind of discovery you make once in your research life.”

Secrets of ancient stars

The title of the most massive black hole in our galaxy will always go back to Sagittarius A*, the supermassive black hole at the center of the Milky Way, which has a mass of about 4 million times the mass of the Sun, but that's because it's a supermassive black hole. A supermassive black hole, not a stellar black hole.

The process by which supermassive black holes form is not well understood, but one theory suggests it happens When huge cosmic clouds collapse. Stellar black holes form when massive stars die. So, Gaia BH3 is the most massive black hole in our galaxy, which was formed as a result of the death of a massive star.

The mass of stellar black holes observed across the Milky Way Galaxy is about 10 times the mass of the Sun on average. Until the discovery of Gaia BH3, the largest known stellar black hole in our galaxy was Cygnus X-1, which has a mass of 21 times the mass of the Sun. While Gaia BH3 is an exceptional discovery within our galaxy by astronomers' standards, it is similar in mass to objects in galaxies far, far away.

Scientists believe that stellar black holes with masses like Gaia BH3 formed when metal-poor stars collapsed. These stars, which have hydrogen and helium as their heaviest elements, are thought to lose less mass over the course of their lives, so they ultimately contain more material that can give rise to a high-mass black hole.

But astronomers were unable to find evidence directly linking high-mass black holes to metal-poor stars until they found Gaia BH3.

Double stars tend to be similar in composition, the study authors said. According to expectations, the researchers found that the star orbiting Gaia BH3 was metal-poor, which means that the star that formed Gaia BH3 was most likely the same one.

“What amazes me is that the chemical composition of the companion is similar to what we find in ancient, metal-poor stars in the galaxy,” Elisabetta Cavao, co-author of the study and a member of the Gaia collaboration at the Paris Observatory, said in a statement.

The star orbiting Gaia BH3 likely formed in the first 2 billion years after the Big Bang created the universe 13.8 billion years ago. The star's path, which moves in the opposite direction to many stars in the Milky Way's galactic disk, indicates that it was part of a small galaxy that merged with the Milky Way more than 8 billion years ago.

Now, the team hopes the research will allow other astronomers to study the massive black hole and reveal more of its secrets without having to wait for the rest of Gaia's data, scheduled for release in late 2025.

“It is impressive to see the transformative impact Gaia is having on astronomy and astrophysics,” Carol Mundell, ESA's science director, said in a statement. “Its discoveries reach far beyond the mission’s original goal, which was to create an extremely accurate, multi-dimensional map of more than a billion stars throughout the Milky Way.”