9 September 2020

Stars are hot spheres composed largely of hydrogen, formed from interstellar gas. They fill galaxies and are a crucial source of energy in planetary systems, providing energy for processes occurring on the planets that typically orbit them. Stars function based on thermonuclear fusion, which involves the conversion of hydrogen into helium in the stellar core. This process produces energy that causes the star to glow and heats the surfaces of the planets orbiting it. The larger the star, the more hydrogen it converts into helium; the largest stars die quickly, while the smallest live for up to several billion years. Once a star exhausts its hydrogen reserves, it dies, resulting in planetary nebulae. However, this death can occur in various ways. Sun-like stars swell to enormous sizes at the end of their lives, engulfing adjacent planets, ultimately transforming into a nebula of very loose material, with the planet itself remaining at its center. a white dwarf, a remnant of a stellar core. Other stars end their lives in a more spectacular way, becoming supernovae, and then immediately becoming black holes, which absorb surrounding matter with their gravity, because the matter in such gravitationally collapsed stars is degenerate because it is under enormous pressure from its own mass.