A database of white dwarfs has been analyzed. Knowledge of the mass and surface gravity of a star, allows calculation of its radius. A team that compared 40,000 white dwarfs to the mass-radius relation for white dwarfs discovered that most of them followed that relation. Eight exceptions were much smaller in size and matched predictions for a strange dwarf. See also Stellar classification References Further reading – Original scientific paper source – Simpler breakdown of said scientific paper. Quark stars Hypothetical stars Exotic matter Strange quark