| definition |
A member of a class of stars to which the Sun belongs. The G-type stars on the main
sequence have surface temperatures of 5,300-6,000 K and therefore appear yellow in
color. G type giant stars (such as Capella) are almost 100-500 K colder than the corresponding
main sequence stars. G type supergiants have temperatures of 4,500-5,500 K. The spectrum
of early type G stars, such as the Sun (G2), is dominated by ionized lines of calcium
(H and K lines, mainly) and neutral metals. In later type G stars the molecular bands
of CH molecules and CN molecules become visible. The main sequence and giant stars
have masses of ~ 1 solar mass, while the supergiants are of ~ 10 solar masses. The
luminosities of G-type giants are almost 30-60 times greater than that of the Sun,
whereas the supergiants are 10,000-30,000 times more luminous.
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