Noun
English Wikipedia has an article on:spectral classWikipedia
spectral class (plural spectral classes)
(astronomy) A classification of stars depending on their spectra and luminosity; usually one of O, B, A, F, G, K, M.
Outside intelligences, exploring the Solar System with true impartiality, would be quite likely to enter the Sun in their records thus: Star X, spectral class G0, 4 planets plus debris. Isaac Asimov