Near Earth Black Hole found

Marijn

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1000 lightyears that is. The previous closest one was V616 Monocerotis at 2800 lightyears. I assume the radius of the event horizon is the same as other 4 solar mass black holes, which would be almost 12km.

Here's a translation from the local media:

European astronomers have found a black hole near Earth. It is located near two stars that can be seen with the unaided eye from the southern hemisphere.

The European Southern Observatory (ESO) released the discovery on Wednesday. The black hole is only 1,000 light-years away from Earth. Never before had a black hole been found so close in the universe. It is part of HR 6819, a two star system. When the scientists studied those two stars, they discovered that one of the two stars orbited an unknown and invisible object in 40 days. That object is at least four times heavier than our sun. "That can only be a black hole," the researchers said.
 

Artlav

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Hm, about as far as they went in one of Stanislaw Lem stories. Slower than light, with return facilitated by time-travel via the black hole.
 

MikeB

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Idle thought:
How far away from the sun could a black hole this size be and not be detected by its effects on outer planets' trajectories? For instance Alpha Centauri A/B add up to about 2 solar masses and are about 4.5 light years away; they presumably have no detectable effect on Pluto/Charon.
 

Michkov

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Depends on its size, lately I've seen speculation that Batygins planet 9 may be a tiny black hole. The hypothetical planet should be out at 600AU with 5 to 10 Earth masses, that would be a hole in the cm size region.
 

Urwumpe

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Depends on its size, lately I've seen speculation that Batygins planet 9 may be a tiny black hole. The hypothetical planet should be out at 600AU with 5 to 10 Earth masses, that would be a hole in the cm size region.

I would rather bet on a planet, how could such a black hole with such a small mass be formed?



That is about 40000 times smaller than even the theoretical limit of a stellar black hole (0.7 solar masses). And even that theory has a lot of weird assumptions on how stars can collapse.
 

Michkov

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Me too, I just gave the numbers so nobody had to ask.

As you say the problem is that we dont have any mechanism such a small hole can from apart from decaying to the size, if they do. Even then I dont know if the timescale matches up with the age of the universe.
 
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