An Etymological Dictionary of Astronomy and Astrophysics

A group into which stars may be classified according to the characteristics of their spectra. Spectral type correlates with the star’s
→ effective temperature and → color.
There are seven main spectral types. From hot
and blue to cool and red, they are O, B, A, F, G, K, and M. Each spectral type is divided into several subtypes. For example, from warmest to coolest, spectral type G is G0, G1, G2, G3, and so on to G9. A precise → spectral classification requires determining the → luminosity class. The Sun is spectral type G2 V.

See also: → spectral; → type.