Hertzprung-Russell diagram
The Hertzsprung-Russell diagram plots stars by absolute magnitude and spectral type. Most stars lie on the main sequence, a curve stretching from hot, bright, blue stars of types O and B to cool, dim, red stars of types K and M.
Hertzsprung-Russell diagram
astronomy
Also known as: H-R diagram
Hertzsprung-Russell diagram, in astronomy, graph in which the absolute magnitudes (intrinsic brightness) of stars are plotted against their spectral types (temperatures). Of great importance to theories of stellar evolution, it evolved from charts begun in 1911 by the Danish astronomer Ejnar Hertzsprung and independently by the U.S. astronomer Henry Norris Russell. On the diagram stars are ranked from bottom to top in order of decreasing magnitude (increasing brightness) and from right to left by increasing...