SOLAR SYSTEM

Detailed explanation-1: -After a low-or medium-mass star has become a red giant, the outer parts grow bigger and drift into space, forming a cloud of gas called a planetary nebula. The core of the star that is left behind cools and becomes a white dwarf. The white dwarf eventually runs out of fuel and dies as a black dwarf.

Detailed explanation-2: -Eventually the core of the star runs out of hydrogen. When that happens, the star can no longer hold up against gravity. Its inner layers start to collapse, which squishes the core, increasing the pressure and temperature in the core of the star.

Detailed explanation-3: -Once at the red giant stage, a star might stay that way for up to a billion years. Then the star will slowly contract and cool to become a white dwarf: Earth-sized, ultra-dense star corpses radiating a tiny fraction of their original energy.

Detailed explanation-4: -A star is born when the gas and dust from a nebula become so hot that nuclear fusion starts. Once a star has “turned on” it is known as a main sequence star. When a main sequence star begins to run out of hydrogen fuel, the star becomes a red giant or a red super giant.

Detailed explanation-5: -Once a star’s core runs out of hydrogen, however, that state of equilibrium is lost and the core begins to collapse. As the core collapses, the shell of plasma surrounding the core becomes hot enough to begin fusing hydrogen itself.

Detailed explanation-6: -A star like our Sun will become a white dwarf when it has exhausted its nuclear fuel. Near the end of its nuclear burning stage, such a star expels most of its outer material (creating a planetary nebula) until only the hot (T > 100, 000 K) core remains, which then settles down to become a young white dwarf.