There are about 100 billion stars in our galaxy. Imagine taking twenty percent of those stars and stuffing them into one, single black hole. That would be one hell of a black hole.
Well, there is such a black hole, called OJ287 (no relation to the ex foot ball star/murderer). It is about 3.5 billion light years away.
What is interesting about OJ287 is that there is so much gravity going on here .... between this massive black hole and a smaller black hole that orbits it ... that you have to measure the orbital dynamics using Einsteinian calculations, which makes it a test of one of Einstein's theories.
(It turns out Einstein was right, as usual. What a brainy guy he was.)
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The Milky Way has a roughly 3 million solar mass black hole at its center.
The nearby M87 galaxy in the Virgo cluster has a roughly 3 billion solar mass black hole at its center.
How much more massive do black holes get?
“Man is something that shall be overcome. Man is a rope,tied between beast and overman - a rope over an abyss.What is great in man is that he is a bridge and not an end.” -Friedrich Nietzsche
Why do black holes stick around in galaxies despite their violent dynamical history?
A brilliant young postdoc has an answer!
Why is it that on hot days, the Free-Ride offspring take up the question of how animals stay warm on cold days? Does this kind of consideration make the heat seem more desirable?
Wow! It's so big that it has a regular black hole in orbit? Crazy stuff, good thing it is far away.