Most compact stars are at the end of theirstellar evolution. They are calledstellar remnants: the form of the remnant depends mainly on the mass of the star when itformed. These objects are small for their mass. Astronomic objects with an unknown nature are often calledcompact star, when evidence suggests that they are verymassive and that they have a smallradius. A compact star which is not a black hole is sometimes called adegenerate star.
