Earth’s purported ‘nearest black hole’ isn’t a black hole

A contested multiple star system is a missing link in stellar evolution

illustration of two blue stars in star system HR 6819

The star system HR 6819 (illustrated) hosts no black holes, as previously reported, but instead two blue stars, one that recently siphoned gas off the other.

L. CALÇADA/ESO

The closest black hole to Earth is not a black hole at all. Rather than being a single star with a black hole, scientists once thought there was a stellar triplet — two stars and a black hole — when in fact it’s just a pair of suns in their early stages of development.

A group of astronomers announced in May 2020 that the star system HR 6819 is most likely made up of a bright, big star locked in a tight, 40-day orbit with a nonfeeding, invisible black hole, as well as a slower-moving companion.

That would make it the closest black hole to us, at about 1,000 light-years from Earth (SN: 5/6/20). However, other teams examined the same data and drew a different conclusion: There are just two stars in the system and no black hole.