Asesmel atraw

Tamudemt (n umeskan n Hertzsprung–Russell) immal-d alkam agejdan deg usesmel n yitran d igmamen n tfukt gar-asen. Agellus aglawan yemmal-d tiggayin n waylal ayen yennumken taẓɣelt n tjumma n yitri (d tin yulin deg tama tayeffust, d tin yudren deg tama tazelmaṭ), ma d agellus aratak yettak-d isig n waffaw n yetri s wassaɣ ɣer waffaw n tfukt, dɣa isig-nni yessaweṭ deg yixef n usuneɣ ɣer 500.000 n tikkal ugar n waffaw n tfukt.

izerɣi A yettwasesmel d A1V ma d awhim yettwasesmel d DA2

Asesmel atraw deg tasnallunt iga d asesmel n yitran s unect n teskanin-is tiylalanin, anda tafesna n yitri taylalant tga d tafesna n yitri i d-igellmen as-ioni deg tissi tuffiɣt n yitri, anda i d-ittili usurres n ibelkimen i wakken ad brun i tafat ayen i d-ittaken tarrayt tallilt i wakat n teẓɣelt n tjumma n yitri.
Tettili-d tesladt n tafat i d-ittaken seg yitri s usefturi n isegra-ines sɣur n yiẓiki n wakkad, i wakken ad yili usefruri n ifutunen i d-ittasen s talɣa n ijerriden n tafat tla (tesɛa) initen n teslit n wenẓar yennebran s ijerriden n weskaf. Yal ajerrid n weskaf yemmal-d a-ion n kra uferdis akruran, dɣa tilin n ijerriden-a deg waggwa (aylal) yesskanay-d taẓɣelt n yitri yessemdayen ɣef wa-ion.
Imir-a, tuget n yitran ttwasisemlen s usemres n isekkilen O, B, A, F, G, K, M anda itran O ig ẓeɣlen yakk sin akin ṭṭafarent-id wid i d-izgan deffir-is alamma d asekkil M iga d asemmaṭ yamk gar-asen, s umata itran n O ttilin d izegzawen, B d izegzawen mellulen, A d imellalen, K d ičinayen, M d izeggaɣen maca ini n yitri yezmer ad yemgarad cwiya s unect n teẓɣelt-is d teskanin-is
Deg unagraw n usesmel n yitran amiran (igan d asesmel n Morgan–Keenan) tettili-d tmerniwt n wuṭṭunen seg 0 alammad 9 ɣer usekkil i d-immalen aylal (O B A F G K M) i wakken ad immal amraw (1/¹⁰) gar n sin n isekkilen imṭafaren, Amedya A5 uga d smus n imrawen gar n A0 d F0. Yerna yella usesmel niden ittwagber daɣen deg usesmel n Morgan–Keenan, aya iga d tadusi n waffaw s isekkilen yettwasnemlen s isekkilen iṛumaniyen I II III IV V

Tilmas n yitran

Amagday agejdan: Alkam agejdan

Llant waṭas n telmas d wanawen n yitran. Dɣa wid yettarran ahidṛujin s talɣa turmidt s uzday aɣisan ɣer uhilium deg tlemmast-is ttwasemman itran n welkam agejdan, Talmest-a tga d tallit tamezwarut seld n tlallit akken ilant (sɛant) tasuddest takrurant yecban tasuddest n tfukt, itri ameqqran yakk deg ubleɣ gar n yitran n welkam agejdan d win ilan akdu meqqren d teẓeɣt yeflalen (ini-ines d azegzaw). Ableɣ n yitran-a yettili gar n 5% n ubleɣ n tfukt (azal n 109 n tegnit) i yitran yettilin s ddaw n welkam agejdan alamma d 10 n tikkal n ukdu n tfukt (itran izegzawen) ma d taẓɣelt tajummant tettili gar n 3.000° C (izeggaɣen) alamma d 50.000° C (izegzawen d imellalen).
Deg tazwara n tsut tis 20 imesnullanen bṭan itran ɣer 7 n tegrawin akken ifkan isekkilen ilatinen d azamul i d-immalen taẓɣelt tajummant.