radebandi-ye Morgan-Keenan (#)
Fr.: classification de Morgan-Keenan
A system of → spectral classification introduced in 1943 by William W. Morgan (1906-1994), Philip C. Keenan (1908-2000), and Edith M. Kellman (1911-2007) at Yerkes Observatory. Also known as the MK (or MKK) classification or the → Yerkes system.
Named after the two main astronomers, as above; → classification.