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LCOGT's Star In A Box app demonstrates the life cycle of a star and allows you to choose the initial mass of a star and follow it through its life.
Having the information about spectral types was useful, but astronomers wanted to look for trends in the data. In 1911 Ejnar Hertzsprung plotted the absolute magnitude of stars against their colors. Two years later Henry Norris Russell independently did a similar graph using spectral types.