a two-dimensional graph, devised independently by Ejnar Hertzsprung (1873–1967) and Henry Norris Russell (1877–1957), in which the absolute magnitudes of stars are plotted against their spectral types. Stars are found to occupy only certain regions of such a diagram.
Hertzsprung–Russell diagram in other Oxford dictionaries
Definition of Hertzsprung–Russell diagram in the US English dictionary
Hertzsprung–Russell diagram, nearby words in English