What happens when a red giant star becomes a white dwarf?

Question

Audrey Arnold · Accepted Answer

A star becomes a white dwarf when fusion reaction stop.

When the fuel runs out and the star's mass falls below approximately eight times that of the sun, carbon fusion cannot be initiated and the star collapses into a white dwarf. At that point, the star is primarily composed of carbon and oxygen and ceases to produce energy through fusion reactions. Initially, the red giant star is fusing hydrogen and helium to produce mostly carbon and oxygen.

Madeline Arroyo · Answer

undefined A red giant star that transforms into a white dwarf loses its outer layers, which are ejected into space and form a planetary nebula. The star's remaining core contracts and gets very dense, reaching temperatures of about 100,000 Kelvin. This white dwarf core then cools over billions of years to become a black dwarf because it is no longer undergoing nuclear fusion.