English: A Hertzsprung–Russell diagram, showing the luminosities and surface temperatures at which many classes of pulsating stars are found. Additional lines indicate where stars are found when they first fuse hydrogen into helium (zero-age main sequence, ZAMS), evolutionary tracks for stars of masses between 1 and 10 times that of the Sun, and the track along which a typical white dwarf of about 60% the Sun's mass cools.