Rịba ama amaokwu a dị n'okpuru ma zaa ajụjụ ahụ mgbe e mesịrị n'otu asụsụ ahụ dị ka amaokwu ahụ:  Passage: "Anchor" standards nke na-akọwa MK classification grid maka O-type main-sequence stars, i.e. ndị standards nke agbanwebeghị kemgbe mmalite narị afọ nke 20, bụ 15 Monocerotis (O7 V) na 10 Lacertae (O9 V). The Morgan<unk>Keenan<unk>Kellerman (MKK) "Yerkes" atlas site na 1943 depụtara O-type standards n'etiti O5 na O9, mana naanị kewara klas luminosity maka O9s. Ụkpụrụ abụọ nke MKK O9 V bụ Iota Orionis na 10 Lacertae. Ụkpụrụ Yerkes e degharịrị edegharị ("MK") nke edepụtara na Johnson & Morgan (1953) egosighi mgbanwe ọ bụla na ụdị O5 ruo O8, ma depụta ụkpụrụ 5 O9 V (HD 46202, HD 52266, HD 57682, 14 Cephei, 10 Lacertae) na ụkpụrụ 3 O9.5 V (HD 34078, Sigma Orionis, Zeta Ophiuchi). Nnyocha dị mkpa nke Morgan & Keenan (1973) mere banyere nhazi ụdịdị dị iche iche depụtara ụkpụrụ "MK" maka O4 ruo O7, mana ọzọ enweghị nkewa nke ụkpụrụ site na klaasị luminosity. Nyocha a depụtara "ụkpụrụ dagger" nke isi usoro nke O9 V maka 10 Lacertae na O9.5 V maka Sigma Orionis.  Ajụjụ: Gịnị ka e ji ụkpụrụ Iota Orionis na 10 Lacartae mee?
MKK O9 V