Close Black Hole

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Close Black Hole

Black holes are everywhere — there could be a hundred million in the Milky Way Galaxy alone. And the closest one yet seen isn’t all that far away — just 1,560 light-years.

Astronomers discovered that one in observations from the Gaia spacecraft. It’s plotting the positions and motions of more than a billion stars. But it’s also making many new discoveries.

One of them is Gaia BH1 — its first black hole. Its images showed a star a lot like the Sun. The star was moving back and forth a bit — likely because of the gravitational pull of a companion. But Gaia didn’t see a companion. Neither did follow-up observations by other telescopes.

The companion had to be a black hole about 10 times the mass of the Sun. It’s probably the remnant of a star that started at about 20 times the Sun’s mass. The star’s core collapsed to form the black hole, while its outer layers blasted into space as a supernova.

The star and black hole are separated by about the same distance as Earth to the Sun. That’s the widest gap between the members of a black-hole binary system yet seen. And that’s a puzzle. Computer models say the two objects should be much closer. So astronomers are working to figure out what’s happening with this nearby black hole.

Gaia BH1 is in Ophiuchus the serpent bearer. The constellation is in the southeast at first light, to the upper left of the Moon. Gaia BH1 is far too faint to see without a telescope.

Script by Damond Benningfield

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