Giant star

A giant star has a substantially larger radius and luminosity than a main-sequence (or dwarf) star of the same surface temperature.^[1] 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.^[2] The terms giant and dwarf were coined for stars of quite different luminosity despite similar temperature or spectral type (namely K and M) by Ejnar Hertzsprung in 1905^[3] or 1906.^[4]

Giant stars have radii up to a few hundred times the Sun and luminosities between 10 and a few thousand times that of the Sun. Stars still more luminous than giants are referred to as supergiants and hypergiants.

A hot, luminous main-sequence star may also be referred to as a giant, but any main-sequence star is properly called a dwarf, regardless of how large and luminous it is.^[5]

^ Patrick Moore, ed. (2002). "Giant star". Astronomy Encyclopedia. New York: Oxford University Press. ISBN 0-19-521833-7.
^ John Daintith and William Gould, ed. (2006). giant (5th ed.). New York: Facts On File, Inc. ISBN 0-8160-5998-5.
^ Russell, Henry Norris (1914). "Relations Between the Spectra and Other Characteristics of the Stars". Popular Astronomy. 22: 275–294. Bibcode:1914PA.....22..275R.
^ Brown, Laurie M.; Pais, Abraham; Pippard, A.B., eds. (1995). Twentieth Century Physics. Bristol, UK; New York, NY: Institute of Physics, American Institute of Physics. p. 1696. ISBN 0-7503-0310-7. OCLC 33102501.
^ Jacqueline Mitton, ed. (2001). Giant star. Cambridge: Cambridge University Press. ISBN 0-521-80045-5.

[oxford-1] Patrick Moore, ed. (2002). "Giant star". Astronomy Encyclopedia. New York: Oxford University Press. ISBN 0-19-521833-7.

[fof-2] John Daintith and William Gould, ed. (2006). giant (5th ed.). New York: Facts On File, Inc. ISBN 0-8160-5998-5.

[HRN-3] Russell, Henry Norris (1914). "Relations Between the Spectra and Other Characteristics of the Stars". Popular Astronomy. 22: 275–294. Bibcode:1914PA.....22..275R.

[Brown-Pais-Pippard-1995-4] Brown, Laurie M.; Pais, Abraham; Pippard, A.B., eds. (1995). Twentieth Century Physics. Bristol, UK; New York, NY: Institute of Physics, American Institute of Physics. p. 1696. ISBN 0-7503-0310-7. OCLC 33102501.

[cambridge-5] Jacqueline Mitton, ed. (2001). Giant star. Cambridge: Cambridge University Press. ISBN 0-521-80045-5.

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