Giant Stars

large stars (100-1,000 times larger than the sun) of great luminosities (100-1,000 times the sun’s luminosity) forming a branch of giant stars on the Hertzsprung-Russell diagram; the location of the branch on the diagram differs for Population I and Population II stars of our galaxy (primarily because of the difference in masses). Giant stars have small average densities (10^-5—10^-7 g/cm³), owing to the extended rarefied envelopes. Evidently they are the ordinary stars of the main sequence at the later stages of evolution (the stage of helium burning). Some giant stars exhibit corpuscular instability (the efflux of matter from the surface).