A white dwarf is a small, dense star that is the remnant of a star like our Sun after it has exhausted its nuclear fuel. When such a star runs out of hydrogen and helium, it sheds its outer layers, leaving behind a hot core that gradually cools over time. White dwarfs are typically about the size of Earth but contain a mass comparable to that of the Sun.
These stars are primarily composed of carbon and oxygen, and they do not undergo fusion reactions. Instead, they shine due to residual heat. Eventually, a white dwarf will cool and fade, becoming a black dwarf, although the universe is not old enough for any black dwarfs to exist yet.
