A star that formed from an extremely large nebulae may ultimately end up as a black hole. Here the assumption is that the mass of the star formed from the extremely large nebula would be more than 10 times the mass of our sun.
During the main sequence of its life cycle, a star obtains its energy from the nuclear fusion of hydrogen to helium. Over time, the hydrogen runs out in the core, while the fusion continues in the outer envelope. This causes an expansion of the outer envelope and the star becomes a massive red giant. The contraction of the core will cause fusion of helium to carbon and further fusion reactions will ultimately result in the formation of iron. At this stage, this massive star will undergo a brilliant explosion, known as a supernova. This will provide enough light to brighten the part of galaxy for some time. After this reaction, only the core remains and it becomes so dense that its gravity is high enough to capture light. When this happens, even the light is unable to reflect back from the core and we have a black hole--a celestial body of extremely high density and gravity.
Note that for stars with average mass, like our sun, the last stage of the life cycle is white dwarf, while the more massive stars become neutron stars. Only the most massive stars end up as black holes.
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