An Etymological Dictionary of Astronomy and Astrophysics

A diagram showing the relative density of occurrence of stars at various → color-magnitude positions of the → Hertzsprung-Russell diagram for a given → galaxy.

See also: Named after R. Hess who originated it in 1924: “Die Verteilungsfunktion der absoluten Helligkeiten in ihrer Abhängigkeit vom Spektrum”. Probleme der Astronomie. Festschrift fur Hugo v. Seeliger. Springer, Berlin. p. 265; → diagram.