A star becomes a white dwarf when it has exhausted its nuclear fuel and all that remains is the dense inner core, typically made of carbon and oxygen. (kavlifoundation.org)
Our little yellow dwarf star will eventually become a white dwarf instead. (religion.blogs.cnn.com)
Once this fuel is used up, however, the remaining matter is crushed into the center of the star, which becomes a white dwarf. (discovermagazine.com)