A compact star is a star whose density is many times greater than the density of an ordinary star. Compact stars include:
- white dwarfs ;
- neutron stars ;
- black holes ;
- exotic stars (hypothetical).
Inside the compact stars, the nuclear reaction ceased, due to which they are compressed by gravity . White dwarfs and neutron stars form when the pressure of a degenerate gas compensates for gravitational forces. In black holes, gravity is so great that it compresses matter indefinitely.
Compact stars can also be referred to as compact remnants , as they form at the end of a star’s life cycle.