Black hole:The different stages in the formation of 'Block holes'. Let us discuss about them.All stars radiate energy by nuclear fusion is hydrogen. When the supply of hydrogen is almost over for further fusion, the star collapses and core of the star starts to shrink.Stellar Nebula- first stage in the life of all stars,Average Sun-like Star Life Cycle:Red giant: The remaining hydrogen density increases as the star collapse and due to further fusion of remaining hydrogen atoms, heat is evolved and star blows off increasing diameter of the star to several times. This stage of the star is called 'red giant' phase. Planetary nebula:
A nebula consisting of a rapidly expanding shell of glowing gas,mostly hydrogen, ejected from a red giant upon its collapse into awhite dwarf. Ultraviolet radiation from the hot, luminous white dwarfionizes the expanding gas and causes it to glow. The nebuladisappears once the cooling dwarf can no longer ionize it, and itsmaterial eventually returns to the interstellar medium. White dwarf : After a large interval of time (millions of years); hydrogen availability in the star is exhausted. The red giant now blows away or releases material particles in it and becomes 'dim'. This stage of the star is called "white dwarf". In the stage of white dwarf remaining mass of the sun gets packed into a very small volume i.e., 1/〖10〗^6 th1 by 10 power 6thof the original volume increasing density of the star. Further collapse of the star is stopped temporarily.Huge Star Life Cycle:Red Supergiant:Supernova: After exceeding the Chandra Sekhar limit, due to intense gravitational force of attraction material particles in 'core' are crushed together and hence temperature of the star rises over 100 billion degrees. In this stage, the repulsive forces between nuclei overcome the gravitational force and explode in to "supernova". Neutron star: Next to supernova, the remaining core of the stars is under great pressure, due to which electrons are forced to combine with protons producing neutrons throughout the star. This stage is called 'neutron star'Giant Star Life Cycle:Red Supergiant:Supernova:Black Hole: If mass of the original star is very large, say 10 times or more of the sun, even neutrons collapse further and block hole is formed.

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