Compact object

In astronomy, the term compact object (or compact star) refers collectively to white dwarfs, neutron stars, and black holes. It could also include exotic stars if such hypothetical, dense bodies are confirmed to exist. All compact objects have a high mass relative to their radius, giving them a very high density compared to ordinary atomic matter. The term is used as a generalization for cases where the exact nature of a significant gravitational effect isolated to a small radius is not known. Since most compact object types represent endpoints of stellar evolution, they are also called stellar remnants, and accordingly may be called dead stars in popular media reports. The state and type of a stellar remnant depends primarily on the mass of its progenitor star. A compact object that is not a black hole may be called a degenerate star. In June 2020, astronomers reported narrowing down the source of fast radio bursts (FRBs), which may now plausibly include "compact-object mergers and magnetars arising from normal core collapse supernovae".