Israeli Astronomer: Discovery Provides ‘First Indisputable Proof’ of Stellar Black Hole This Massive
Astronomers from Tel Aviv University have helped discover a massive black hole, named Gaia BH3, nearly 33 times the mass of the Sun, making it the largest known stellar black hole in the Milky Way galaxy. The previous record-holder was a stellar black hole in the Cygnus constellation with a mass 20 times that of the Sun.
Such objects, of course, cannot compete in heft with the supermassive black hole at the galaxy’s center, Sagittarius A*, which has a mass 4.154 million times that of the Sun.
Gaia BH3 is currently relatively close to our solar system—around 2,000 light-years away, in the constellation Aquila. The Milky Way spans about 100,000 light years in diameter. The black hole has a companion star that orbits it, allowing for its detection. This discovery was part of the European Space Agency’s Gaia mission, which is mapping the stars of our galaxy.
Dr. Tsevi Mazeh from Tel Aviv University, a co-author of the study describing the discovery, explains that stellar black holes form from the gravitational collapse of a single star. Gaia BH3, identified through the wobbling of its companion star, was further studied with data from the European Southern Observatory’s Very Large Telescope among other facilities.
“Gaia BH3 is the very first black hole for which we could measure the mass so accurately,” Mazeh said. “At 30 times that of our Sun, the object’s mass is typical of the estimates we have for the masses of the very distant black holes observed by gravitational wave experiments. Gaia’s measurements provide the first indisputable proof that black holes this heavy do exist.”
The black hole and its companion star are unique because they orbit the Milky Way in a direction opposite to most stars. This suggests that Gaia BH3 formed from a star with low metallicity, similar to stars from the early universe, about 2 billion years after the Big Bang. This star eventually exploded as a supernova, leading to the formation of the black hole.
The companion star is about 76% the mass of the Sun. Its orbit ranges from about 4.5 to 29 astronomical units from Gaia BH3. An astronomical unit, the approximate distance between Earth and the Sun, is defined as 149,597,870.7 kilometers.
