HENRY NORRIS RUSSElL
Henry Norris Russell, director of the Princeton observatory, was one of America's most belovea and distinguished astronomers of this century. His grasp of all phases of astronomy was truly awesome.
In 1912 Russell developed a method of calculating the orbital elements of an eclipsing binary, a method that is still used. He showed how to derive the relative dimensions of the two components and their densities. Beginning in 1903, in collaboration with the British astronomer Hinks, of Cambridge, he undertook a program of deriving stellar parallaxes photographically. The work, which was completed in 1910, was instrumental in his discovery of a relationship between the absolute magnitudes and spectral types of the stars. A plot of this relationship showed the existence of two types of red star: one highly luminous, the other quite faint. By 1913 he had refined this correlation, now known as the Hertzsprung-Russell diagram, and was using the terms giants and dwarfs to distinguish between the two groups.
In the late 1920s Russell applied the newly developed quantum theory to determining the abundances of the elements in stars. From an analysis of the intensity profiles of the solar absorption lines, he derived the relative abundance of some 50 different elements in the solar atmosphere. He also applied this technique to a number of stars. The research revealed the very high abundance of hydrogen in the sun and stars, a result of great importance in our understanding of the role of hydrogen in astrophysical processes. Russell also made important contributions to the theory of stellar structure. He showed that the physical properties of a star can be found solely from its mass and chemical composition (the Vogt-Russell theorem).
