Black holes by supernova

Firstly, a black hole isn't really a hole at all, but that's the easiest way to think of its effects on the rest of the universe. Take a star that's at least thirty times larger than our sun and make it explode (called a supernova). Stars do that at the end of their lifetime, sometimes leaving a remnant of the violent explosion. The nature of the remnant depends on its mass. If the remnant is less than 1.4 solar masses, it will become a white dwarf, a kind of hot dead star that isn't bright enough to visibly shine. If the remnant is roughly 1.4 solar masses, it will collapse. The protons and electrons will be squished together, and their elementary quarky particles will recombine to form neutrons. What you would get is small (by stellar terms) sphere of neutrons with perhaps a thin film of electrons and other stuff at its surface. That's why it's called a neutron star. See, the neutrons don't mind hanging around near each other; but if you get them close enough to each other, they get anxious and resist being pushed any closer. (Yes, I'm attributing emotions to sub-atomic particles.) The neutrons of a neutron star are, indeed, pressed quite close to one another and exert a certain pressure on each other. This pressure prevents the further collapse of the neutrons star. If the remnant is larger than 3 solar masses, it becomes a black hole (well, 2 or 3 depending on who's giving you the number). I think that calculates out to a star roughly 30 solar masses before supernova.

http://oposite.stsci.edu/pubinfo/pr/96/23.html

htmlFor example, let's pick Eta Carin , a superstar that is hundreds of times larger than the sun (also 8,000 ly away) and happened to have exploded around 1850ad.2 That and I have a nice current picture of it. Very well, Eta Carin goes supernova! In a supernova the atmosphere of a star collapses onto and compresses its core, and the remaining mix of stuff is blown into space leaving a remnant of the core. During the earlier part of the star's life, it fused hydrogen into helium. During the later part of its life, it fused helium into the heavier elements, which made their way to the core of the star. In the last split second of its life, as waves of energy push out from the collapsing core, the star fuses its atmosphere of helium (and a few other things) with its core of iron. This is called nucleosynthesis. This process created ALL the atoms heavier than iron in this universe. These heavier atoms plus millions of neutrinos are thrown out in waves as the star collapses, leaving the remnant.

Now, since Eta Carin 's remnant is larger than three solar masses, the pressure of collapse and the force of gravity of all that mass squishing the core (which is very hot metal) condenses all the matter together. No more electron shells and orbits --- the neutrons are forced together. Then, the very neutrons themselves give up and get squished by the pressure, and the star keeps on collapsing. See, there's this certain radius that determines whether the star can squish itself into a black hole. It's called the Schwarzschild Radius (swar - shild). If the starstuff can collapse itself