Compact star

In astronomy, the term compact star (sometimes compact object) is used to refer collectively to white dwarfs, neutron stars, other exotic dense stars, and black holes.

Most compact stars are the endpoints of stellar evolution and are thus often referred to as stellar remnants, the form of the remnant depending primarily on the mass of the star when it formed. These objects are all small in volume for their mass, giving them a very high density. The term compact star is often used when the exact nature of the star is not known, but evidence suggests that it is very massive and has a small radius, thus implying one of the above-mentioned categories. A compact star that is not a black hole may be called a degenerate star.

Formation

The usual endpoint of stellar evolution is the formation of a compact star.

Most stars will eventually come to a point in their evolution, when the outward radiation pressure from the nuclear fusions in its interior can no longer resist the ever present gravitational forces. When this happens, the star collapses under its own weight and undergoes the process of stellar death. For most stars, this will result in the formation of a very dense and compact stellar remnant, also known as a compact star.