White Dwarf Star

This is a star, about the size of Earth, however it weighs as much as the Sun. It is prevented from shrinking. Electrons that are free can be packed so close together. In more massive stars the barrier can be broken when protons combine with their electron counterparts. The first white dwarf was the companion to Serius. They are in the same orbit. They are both equal to the Sun in size. They are hard to detect because they are so dim. This is the last phase of a medium mass star.