How massive is a 100 kilometres diameter black hole? What will happen if a 100 kilometres diameter black hole appear near Sun?

 Okay for context, if our sun became a black hole at this moment, it would have a diameter of 3km. determined by its Schwarzschild radius, which is the radius of the event horizon, or the "point of no return" for light.

Yeah.. that sets the tone for a 100km diameter blackhole. It would have a mass of about 34 times the mass of the Sun. It would be classified as a stellar-mass black hole. Currently the most massive Stellar-mass BH we know in our galaxy is Gaia BH3 with about 32x solar mass, but of course, in our scenario, our BH tops the rank of stellar-mass BHs.

It would definetly disrupt our solar system, possibly causing every object here to fall into it or get ejected into outer space.. and might even disrupt the path of other star systems.

Though honestly, it is still nothing compared to the blackholes found in the centure of galaxies, called Supermassive blackholes such as our milky way’s known as Sagittarius A*. It has a mass of 4.1 MILLION times the mass of our sun and has a radius of 12 MILLION KILOMETER. They are in a league of their own, both technically and figuratively.

Mind boggling numbers huh…