The Sun is a G-Type main sequence star. Does that mean there is an “A-Type”, “B-Type”, ect.?
Yes, with conditions. The star types now are called by letter types. From hottest to cooler, the sequence is O, B, A, F, G, K, M (Mnemonic: “Oh, Be A Fine Girl, Kiss Me”). The following is from “http://en.wikipedia.org/wiki/Stellar_cl… The reason for the odd arrangement of letters is historical. An early classification of spectra by Angelo Secchi in the 1860s divided stars into those with prominent lines from the hydrogen Balmer series (group I, with a subtype representing many of the stars in Orion); those with spectra which, like the Sun, showed calcium and sodium lines (group II); colored stars whose spectra showed wide bands (group III); and carbon stars (group IV). In the 1880s, the astronomer Edward C. Pickering began to make a survey of stellar spectra at the Harvard College Observatory, using the objective-prism method. A first result of this work was the Draper Catalogue of Stellar Spectra, published in 1890. Williamina Fleming classified most of the spectra in this catalogue.
