Astronomers at the International Gemini Observatory in Hawaii discovered a black hole that is 1,600 light-years away and 10 times bigger than our Sun —making it the closest known black hole to Earth.
It is the first dormant black hole astronomers have found in the Milky Way, which raises questions about the formation of binary star systems.
“We could find no plausible astrophysical scenario that can explain the observed orbit of the system that doesn’t involve at least one black hole,” said Kareem El-Badry, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, in a statement.
Researchers discovered the black hole in the constellation Ophiuchus and dubbed it Gaia BH1, after analyzing data from the European Space Agency’s Gaia spacecraft to identify its location. The spacecraft recorded strange movements in the path of a star, which could only be caused by the gravity of an unseen and massive object.
The black hole was likely once a star 20 times larger than our Sun. Theories about how black holes are formed say this Sun should have obliterated or disrupted its companion when it puffed into a supergiant or exploded in a supernova. Yet the star, which orbits the black hole at the same distance as the Earth orbits the Sun, is doing well these days.
“While this potentially augurs future discoveries of the predicted dormant black hole population in our galaxy, the observations also leave a mystery to be solved — despite a shared history with its exotic neighbour, why is the companion star in this binary system so normal?” said El-Badry.