Astronomers at the European Southern Observatory have found the closest black hole to Earth yet, so near that the two stars dancing with it can be seen by the naked eye.

Of course, close is relative on the galactic scale. This black hole is about 1,000 light-years away, which equates to roughly 9,500 trillion kilometres.

But in terms of the cosmos and even the galaxy, it is in our neighbourhood, according to a study lead by astronomer Thomas Rivinius, who led the study.

The previous closest black hole is probably about three times further, about 3,200 light-years, he said.

The black hole is tiny, only 40 kilometres in diameter, and lives in the Telescopium constellation (the telescope), which neighbours the Sagittarius and Corona Australis constellations in the southern celestial hemisphere.

https://www.abc.net.au/news/2020-05-07/astronomers-discover-closest-black-hole-to-earth-ever/12222154

Only 13 hours late.

40 kilometres in diameter, how many solar masses is that going to be equivalent too?

sibeen said:

40 kilometres in diameter, how many solar masses is that going to be equivalent too?

R_s=2GM/c²

where G is the gravitational constant, M is the object mass, and c is the speed of light

ChrispenEvan said:

sibeen said:

40 kilometres in diameter, how many solar masses is that going to be equivalent too?

R_s=2GM/c²

where G is the gravitational constant, M is the object mass, and c is the speed of light

ChrispenEvan said:

ChrispenEvan said:

sibeen said:

40 kilometres in diameter, how many solar masses is that going to be equivalent too?

R_s=2GM/c²

where G is the gravitational constant, M is the object mass, and c is the speed of light

so just transpose for M

ChrispenEvan said:

ChrispenEvan said:

sibeen said:

40 kilometres in diameter, how many solar masses is that going to be equivalent too?

R_s=2GM/c²

where G is the gravitational constant, M is the object mass, and c is the speed of light

‘bout 7.

ChrispenEvan said:

ChrispenEvan said:

ChrispenEvan said:

R_s=2GM/c²

where G is the gravitational constant, M is the object mass, and c is the speed of light

‘bout 7.

bangs head on desk

I was doing a BOE and scratching my head going “but that’s not dimensionally accurate”.

I then worked out I was using g instead of G.

D’oh!

sibeen said:

40 kilometres in diameter, how many solar masses is that going to be equivalent too?

About 5 or so.

sibeen said:

ChrispenEvan said:

ChrispenEvan said:

‘bout 7.

bangs head on desk

I was doing a BOE and scratching my head going “but that’s not dimensionally accurate”.

I then worked out I was using g instead of G.

D’oh!

I get 14

belay that! I took the diameter for the radius (blush)

From the other thread, the paper (which is quite interesting):

https://www.aanda.org/articles/aa/full_html/2020/05/aa38020-20/aa38020-20.html

I am not dead