Black hole candidate found in an unexpected place

Orbiting most galaxies are hundreds of objects called globular clusters - densely packed star clusters that can contain hundreds of thousands of stars.  The stars that live in globular clusters are typically very old.  Small black holes form when very massive stars die.  These massive stars don't live very long, and since globular clusters contain very old stars, all of the massive stars they contained have likely died and formed black holes.  However, these black holes aren't expected to stick around in the globular clusters they form inside.  Because things are packed so closely together in these clusters, when things get close to each other, one can get slingshotted out.  Astronomers expected this to happen to the vast majority of black holes that form in globular clusters.

Globular cluster M62 contains a newly discovered black hole candidate. (Image credit: NASA, STSci)

Globular cluster M62 contains a newly discovered black hole candidate. (Image credit: NASA, STSci)

Astronomers recently made an exciting discovery, finding two black holes in a globular cluster called M22 that is orbiting our Milky Way.  But until now, it wasn't clear if this discovery was just very lucky, or if other globular clusters hung onto their black holes too.  Astronomers have now discovered a new black hole candidate in globular cluster M62.  If this object is confirmed to be a black hole, we have an entirely new regime in which to hunt for and study these small black holes.  Having a new place to search for these objects would be extremely exciting since at present, astronomers know of only a couple dozen confirmed, stellar-mass black holes.

 

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