Star classification Hertzsprung-Russell diagram Spectral classes Subtypes Main sequence stars - young stars Dwarf stars Yellow dwarf Red dwarf Giant and supergiant stars - old, large stars Red giant Blue giant Supergiant Faint, virtually dead stars White dwarf Brown dwarf Neutron star Pulsar Binary stars Double star Binary star Eclipsing binary X-ray binary star Variable stars - stars that vary in luminosity Cepheid variable stars Mira variable stars ( these will become something in the fueture )