500
Internal pressure from the hydrodynamic forces due to the nuclear fusion reactions in its core. Centripetal/centrifugal forces due to its spin. Also, electron-degeneracy pressure which plays a role when fusion ceases. (Basically, each electron must occupy its own energy state. When electrons are packed together, as they are in a white dwarf, the number of available low energy states is too small and many electrons are forced into high energy states. When this happens the electrons are said to be degenerate. These high energy electrons make a significant contribution to the pressure. Because the pressure arises from this quantum mechanical effect, it is insensitive to temperature, i.e., the pressure doesn't go down as the star cools. This pressure is known as electron degeneracy pressure and it is the force that supports white dwarf stars against their own gravity.)
What prevents a star from collapsing under its own gravity?