compact galaxy

compact galaxy

A member of a class of peculiar galaxies, first catalogued by Fritz Zwicky in the 1960s. Their brightness is so concentrated that they are almost indistinguishable from stars on normal photographs and their constituent stars are unusually hot and blue. Detailed examination has shown that they are either active galaxies, starburst galaxies, or extragalactic H II regions, and the term compact galaxy is now rarely used.