Giant star

A giant star is a star with much larger radius and luminosity than a main-sequence star of the same surface temperature.Giant star. In Astronomy Encyclopedia, ed. Patrick Moore, New York: Oxford University Press, 2002. Giant. In The Facts on File Dictionary of Astronomy, ed. John Daintith and William Gould. 5th ed, New York: Facts On File, 2006. 

Giant stars are up to a few hundred times the diameter of the Sun and between 10 and a few thousand times brighter than the Sun. They do not last as long as most main sequence stars. 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.Giant star. In Cambridge Dictionary of Astronomy, Mitton, Jacqueline. Cambridge University Press 2001.  

There are a wide range of giant class stars, and sub-divisions are often used to identify particular types. Astronomers use such terms as: sub-giants, bright giants, red giants, yellow giants and blue giants. The giant luminosity class is given the Roman numeral III, for bright giants it is II.

 Types of giants 
 Red giants 
These have spectral types K to M.
 Pollux
 Dubhe
 Arcturus
 Aldebaran
 Gacrux

 Yellow giants 
These have spectral types F and G.
 Capella A and B
The Cepheid variables are yellow giants.

 Blue giants 
These have spectral types A, B, and O.
 Alcyone in the Pleiades

 Bright giants 
Giants nearly as bright as supergiants. They can have many spectral types.
 Canopus
 Aludra
 Alpha Herculis

 References 

Category:Types of stars