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American astronomer who studied binary stars and developed methods to calculate their mass and distances. Working independently of Ejnar Hertzsprung, Russell also demonstrated the relationship between types of stars and their absolute magnitude. This correlation is now known as the Hertzsprung-Russell diagram.
American astronomer-one of the most influential during the first half of the 20th century-who played a major role in the establishment of modern theoretical astrophysics by making physics the core of astrophysical practice. Bearing his name is the Hertzsprung-Russell diagram, a graph that demonstrates the relationship between a star's intrinsic brightness and its spectral type and that represents Russell's theory of the way stars evolve.