Groundbreaking discovery: Astronomers find largest black hole in Milky Way

Astronomers have discovered the largest known stellar black hole in the Milky Way, according to a European Space Agency news release.

Named Gaia BH3, it was found by chance when the space agency’s Gaia mission team was combing through data. With a mass 33 times that of the sun, BH3 surpasses the previous record holder, Cyg X-1, which is about 20 solar masses.

“It’s impressive to see the transformational impact Gaia is having on astronomy and astrophysics,” Carole Mundell, ESA director of science, noted in the release. “Its discoveries are reaching far beyond the original purpose of the mission, which is to create an extraordinarily precise multi-dimensional map of more than a billion stars throughout our Milky Way.”

In the Aquila constellation 2,000 light years from Earth, BH3 was detected when scientists noticed a “wobbling” motion in its companion star. The star, slightly smaller than the sun, was orbiting an invisible companion, which turned out to be the massive black hole.

Stellar black holes are formed from the collapse of massive stars at the end of their lives. Unlike supermassive black holes, whose origins remain unknown, stellar black holes are typically smaller. BH3 is considered a “dormant” black hole, because it is too far away from its companion star to strip it of its matter. Its absence of light made it difficult to detect.

The groundbreaking discovery of BH3 challenges our understanding of how massive stars develop and evolve. Astronomers theorize stellar black holes form from metal-poor stars, which lose less mass over their lifetimes, leaving more material after their death. Stellar-mass black holes can continue to gain mass through collisions with other stars and black holes.

Astronomers say much remains to be investigated about BH3′s nature, and they hope further study will aid in our understanding of the formation and evolution of stellar black holes in our galaxy.