Back in the late 1960s, the British astrophysicist Donald Lyndon-Bell deduced that most galaxies must have a supermassive black hole at their hearts. Since then much evidence has emerged to support this idea. In 2018, astronomers even took an image of the black hole sitting at the center of a nearby galaxy called M87.
It turns out that supermassive black holes play a crucial role in the evolution of galaxies by creating the gravitational field that binds stars together. They also swallow nearby dust and gas creating massive jets of energy that themselves create conditions ripe for star formation.
The supermassive black hole at the center of our galaxy has a mass equivalent to about a million suns and a radius about the diameter of Mercury’s orbit around the sun.
But black holes can be much smaller. A black hole with the mass of our Sun would be a few kilometers in size while a black hole with the mass of an asteroid would be the size of a single atom.
There are good reasons to think that black holes in this size range must have been formed early in the universe and that these primordial black still fill the universe.
And that raises an interesting question. If supermassive black holes seed the formation of galaxies, could smaller black holes seed the formation of stars? Could a black hole even sit at the center of our Sun?
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