ExploraTour: A Peek into the Lives of the Stars
The Details of The Collapse of a White Dwarf
When the fuel is used up in the core, there is nothing to oppose gravity and the star begins to collapse. The atoms in the high temperature core are completely ionized. This means they are separated into electrons and ions. Matter in this condition can be compressed to very high densities.
However, quantum theory tells us that no two electrons can be in the same state in the same region in space. By state, we mean energy, direction of spin, and other characteristics.
As the electrons are squeezed together by gravity, the lower energy states are filled and new electrons must be added at higher and higher energies. The matter is being forced into a state called "electron degeneracy".
The pressure that is generated by electron degeneracy opposes the crush of gravity. If the stellar remnant has a mass less than 1.4 solar masses, the degeneracy pressure is enough to balance gravity and the star settles down to form a white dwarf.
