Black holes are formed through a process known as stellar evolution. The formation of a black hole occurs when a massive star undergoes a catastrophic event at the end of its life.
Here are the general stages of black hole formation:
Star Formation: Black holes are typically formed from the remnants of massive stars. These stars have a much larger mass than our Sun, usually more than three times its mass. They form through the gravitational collapse of a dense region in a molecular cloud, where gravity pulls gas and dust together.
Stellar Evolution: Massive stars burn their nuclear fuel much faster than smaller stars. They go through various stages, fusing lighter elements into heavier ones in their cores. As the core runs out of fuel, nuclear reactions cease, causing the core to collapse under its own gravity.
Supernova: When the core of a massive star collapses, it triggers a cataclysmic explosion known as a supernova. The outer layers of the star are expelled into space, while the core collapses inward. The explosion releases an immense amount of energy and creates a shockwave that can disperse the remaining material.
Formation of a Black Hole: If the collapsing core of the star has a mass greater than about three times the mass of the Sun (known as the Tolman-Oppenheimer-Volkoff limit), it will continue to collapse under its own gravity, forming a black hole. The core becomes so dense that it forms a singularity—a point of infinite density—at its center. This singularity is surrounded by an event horizon, a boundary beyond which nothing, not even light, can escape the gravitational pull of the black hole.
It's important to note that black holes can also form through other means, such as the collision of neutron stars or the gravitational collapse of very massive gas clouds in the early universe. However, the process described above is the most common mechanism for the formation of stellar black holes.