Main Sequence of Stars

the totality of stars physically similar to the sun and forming practically a single-parameter sequence on a phase diagram (Hertzsprung-Russell diagram). Along the main sequence of stars on the diagram, stellar luminosities uniformly decrease as surface temperatures decrease; masses and radii decrease (considerably more slowly), but average densities increase. Aside from errors in observation, the observable dispersion of the main sequence depends on differences in the ages of the stars of the same spectral class and a certain difference in chemical composition. Stars of the main sequence are in an early stage of evolution, when their source of energy is the combustion of hydrogen in their interiors.