Giant star

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Hertzsprung–Russell diagram
Spectral type
Brown dwarfs
White dwarfs
Red dwarfs
Subdwarfs
Main sequence
("dwarfs")
("dwarfs")
Subgiants
Giants
Bright giants
Supergiants
Hypergiants
absolute
magni-
tude
(MV)
magni-
tude
(MV)
A giant star is a star with substantially larger radius and luminosity than a main-sequence (or dwarf) star of the same surface temperature. They lie above the main sequence (luminosity class V in the Yerkes spectral classification) on the Hertzsprung–Russell diagram and correspond to luminosity classes II and III. The terms giant and dwarf were coined for stars of quite different luminosity despite similar temperature or spectral type by Ejnar Hertzsprung about 1905.