Astronomers Discover the Closest Known Black Hole
by Megan Gannon/Smithsonianmag.com
The pair of stars in a system called HR 6819 is so close to us that on a clear night in the Southern Hemisphere, a person might be able to spot them without a telescope. What that stargazer wouldn’t see, though, is the black hole hiding right there in the constellation Telescopium. At just 1,000 light-years away, it is the closest black hole to Earth ever discovered, and it could help scientists find the rest of the Milky Way’s missing black holes.
Dietrich Baade, an emeritus astronomer at the European Southern Observatory (ESO) in Germany and co-author of the study in Astronomy & Astrophysics, says the team never set out to find a black hole. They thought the HR 6819 system was a simple binary, made up of two visible stars orbiting each other. But their observations with the MPG/ESO 2.2-meter telescope at ESO’s La Silla Observatory in Chile revealed something stranger: One of the stars orbited an unknown object every 40 days, while the second star revolved around this inner pair.