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As you can see, I have revised this article extensively. I thank all those who contributed to the earlier version of the article. Some of the theories listed, though not what I would agree with, are nevertheless valuable as documents of people's thinking on the subject of the Sun and other subjects.--[[User:TerryH|TerryH]]<sup>[[User talk:TerryH|Talk]]</sup> 13:50, 6 March 2008 (EST)
As you can see, I have revised this article extensively. I thank all those who contributed to the earlier version of the article. Some of the theories listed, though not what I would agree with, are nevertheless valuable as documents of people's thinking on the subject of the Sun and other subjects.--[[User:TerryH|TerryH]]<sup>[[User talk:TerryH|Talk]]</sup> 13:50, 6 March 2008 (EST)
==Spectral Classification 101==
A star's size and colour are determined as follows:
'''Colour:'''
*O = very hot, bright, bluish in colour (most of an 'O' star's output is in the ultraviolet range);
*B = very hot, blue in colour;
*A = hot, bluish-white in colour;
*F = hot, white with a tinge of yellow in colour;
*G = warm, yellow in colour;
*K = cool, orange in colour;
*M = cool, red in colour.
'''Size'''
* '''I''' supergiants
** '''Ia-0''' (hypergiants or extremely luminous supergiants)
** '''Ia''' (luminous supergiants)
** '''Iab''' (intermediate luminous supergiants)
** '''Ib''' (less luminous supergiants)
* '''II''' bright giants
** '''IIa''',
** '''IIab'''
** '''IIb'''
* '''III''' normal giant stars
** '''IIIa'''
** '''IIIab'''
** '''IIIb'''
* '''IV''' subgiant stars
** '''IVa'''
<!--** '''IVab'''-->
** '''IVb'''
* '''V''' main sequence stars (dwarfs)
** '''Va'''
<!--** '''Vab'''-->
** '''Vb'''
* '''VI''' subdwarf stars (rarely used)
* '''VII''' white dwarfs (rarely used)
Thus Sol is a G2 (*yellow*) V (main sequence dwarf) star, not ''"A "V" star in this class is in the fifth level of luminosity&mdasha yellow dwarf star."'' The number after the letter determines the luminosity (and thus temperature) of the star within its colour type - a G0 V star is slightly hotter, brighter, larger and more massive than a G2 V which, in turn, is a lot brighter, hotter, larger and more massive than a G8 V star. [[User:HumbleServant|HumbleServant]] 17:11, 28 April 2008 (EDT)