Astronomers locate new closest black hole to Earth

Black holes are arguably the most fascinating yet violent objects in the known universe, and a Harvard astrophysicist just discovered the closest one to Earth yet. But no need to panic, as even this black hole is still 1,600 light-years away and dormant, at least for now.

Named Gaia BH1, this boundless black hole was discovered when Dr. El-Badry and his research team noticed a star shuttering oddly, indicating that something substantial was amiss. The team later decided to investigate the oddity by utilizing the Gemini North telescope in Hawaii. Surprisingly, they learned that the cause of the disturbance was an entirely new black hole in our own galaxy.

At 10 times the sun’s mass, Gaia BH1 resides in the constellation Ophiucus, meaning that it’s roughly three times closer to Earth than the previously nearest black hole. Aside from its close proximity to Earth, another noteworthy aspect of this new black hole is that it’s currently entirely dormant, meaning that it’s not doing what most black holes are known for, relentlessly gobbling up everything surrounding it.

How active black holes become dormant

Dormant black holes are notoriously difficult to detect since they don’t interact much with their surroundings and don’t emit high levels of X-ray radiation like active black holes. A black hole reaches this point when, over time, all of the stars and other nearby objects have been absorbed, leaving the black hole with nothing to feed on for a prolonged period of time. However, this doesn’t mean that dormant black holes like Gaia BH1 won’t become active again. 

Even dormant black holes still exert extreme gravitational forces on surrounding objects. And while that force may not be strong enough to pull the objects past the event horizon, it will slowly detract energy from those nearby objects. Eventually, this energy loss can cause something like a star to fall past a black hole’s event horizon, ultimately being consumed and awakening the dormant black hole. 

The strange star that orbits this newly discovered black hole 

While the star that circles Gaia BH1 isn’t odd in itself, its relation to the black hole is what’s puzzling astronomers. According to the current understanding of how black holes form, a star would die in a spectacular supernova explosion, a process that would cause significant damage to nearby objects. Despite this, the star orbiting Gaia BH1 appears unaffected by such a process, leaving astronomers wondering if something is incorrect about the leading theories.

It is interesting that this system is not easily accommodated by standard binary evolution models. It poses many questions about how this binary system was formed, as well as how many of these dormant black holes there are out there.

Kareem El-Badry, astrophysicist, Harvard Smithsonian Center for Astrophysics

While the leading theories on how black holes form may not change anytime soon, this new discovery opens the door for some fascinating new ideas regarding the most mysterious objects in the universe.