Cosmic Giant: Milky Way's Most Massive Stellar Black Hole, Gaia BH3, Discovered
September 25, 2025
Astronomers have discovered Gaia BH3, the Milky Way's most massive stellar black hole, weighing 33 solar masses and lurking just 2,000 light-years away.
In a groundbreaking discovery, astronomers using data from the European Space Agency's (ESA) Gaia mission have identified Gaia BH3, the most massive stellar black hole yet found in our Milky Way galaxy. Tipping the scales at an astonishing 33 times the mass of our Sun, this cosmic behemoth lurks relatively close by, just 2,000 light-years away in the constellation Aquila, making it the second-closest known black hole to Earth.
An Unexpected Discovery
The discovery of Gaia BH3 was serendipitous. The team was reviewing Gaia observations in preparation for an upcoming data release when they noticed a peculiar 'wobble' in the path of a companion star. This motion could only be explained by the immense gravitational pull of a massive, unseen object. Unlike many black holes that reveal themselves by consuming matter and emitting X-rays, Gaia BH3 is 'dormant,' making its detection through gravitational influence all the more remarkable.
Key Facts About Gaia BH3
- Staggering Mass: At 33 solar masses, it shatters the previous galactic record for a stellar black hole, which was around 21 solar masses.
- Proximity: Located 2,000 light-years away, it offers an unparalleled opportunity for close-up study.
- Unique Origins: Its companion is a very old, 'metal-poor' star. This suggests Gaia BH3 formed from a massive star with very few heavy elements, a finding that supports theories about black hole formation in the early universe.
- Dormant Nature: It is not actively feeding, making it invisible to X-ray telescopes and harder to detect.
This is the kind of discovery you make once in your research life. So far, black holes of this mass have only ever been detected in distant galaxies.
The existence of Gaia BH3 provides a crucial local analogue for the massive black holes detected through gravitational waves in distant galaxies. Further observations with instruments like the European Southern Observatory's Very Large Telescope (VLT) will help astronomers confirm its mass with greater precision and unravel the story of its formation, offering a new window into the life cycle of the universe's most extreme stars.
Cosmic Giant: Milky Way's Most Massive Stellar Black Hole, Gaia BH3, Discovered - FAQs
Gaia BH3 is the most massive stellar black hole discovered in the Milky Way galaxy, with a mass 33 times that of our Sun.
It was found by observing the unusual 'wobble' of its companion star using data from the European Space Agency's (ESA) Gaia space telescope.
It provides a rare, close-up view of a massive stellar black hole, confirming that such objects can form from metal-poor stars within our own galaxy.
Gaia BH3 is relatively close in cosmic terms, located approximately 2,000 light-years away from Earth in the constellation Aquila.