What are characteristics of white dwarfs?

White dwarfs are the remnants of stars that have exhausted their nuclear fuel and shed their outer layers, resulting in a dense, hot core. They typically have a mass comparable to that of the Sun but are only about the size of Earth, leading to extremely high densities. White dwarfs no longer undergo fusion reactions and gradually cool over time, eventually becoming faint and dark. Their composition often includes carbon and oxygen, and they are supported against gravitational collapse by electron degeneracy pressure.