Meet your new, but shy, galactic neighbor: a black hole left over from the death of a young shooting star.
European astronomers have found the closest black hole to Earth so far, so close that the two stars dancing with it can be seen with the naked eye.
Of course, closeness is relative to the galactic scale. This black hole is about a thousand light years away and each light year is 9.5 trillion kilometers. But in terms of the cosmos, and even the galaxy, it’s in our neighborhood, said European Southern Observatory astronomer Thomas Rivinius, who led the study published Wednesday in the journal Astronomy & Astrophysics. The closest previous black hole is probably about three times as far, about 3,200 light years away, he said.
The discovery of a closer black hole, found in the Telescopium constellation in the southern hemisphere, suggests that there are more of these out there. Astronomers theorize that there are between 100 million and 1 billion of these small, but dense, objects in the Milky Way.
The problem is that we cannot see them. Nothing, not even light escapes the gravity of a black hole. Scientists can usually only detect them when they gobble up sections of a companion star or something else that falls on them. Astronomers think that most black holes, including this newly discovered one, have nothing close enough to swallow. Then they go unnoticed.
Astronomers found this due to a star’s unusual orbit. The new black hole is part of what used to be a three-star dance on a system called HR6819. The remaining two super hot stars are not close enough to be absorbed, but the inner star’s orbit is warped.
Using a telescope in Chile, they confirmed that there was something like four or five times the mass of our sun pulling on the inner star. It could only be a black hole, they concluded.
External astronomers said that makes sense.
“There are very likely to be much closer black holes than this,” said Avi Loeb, director of the Harvard Black Hole Initiative, who was not part of the study. “If you find an ant while scanning a small section of your kitchen, you know there must be many more.”
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