Morgan-Keenan-Kellman system

Morgan-Keenan-Kellman system

[¦mȯr·gən ¦kēn·ən ′kel·mən ‚sis·təm]
(astronomy)
An expansion of the Harvard sequence to include luminosity, whereby a roman numeral is appended to the Harvard class to indicate position on the Hertzsprung-Russell diagram: I for supergiant, II for bright giant, III for giant, IV for subgiant, and V for dwarf or main sequence. Abbreviated MKK system.
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