Realteolai a rugadh in Oyster Bay, Nua-Eabhrac ab ea Henry Norris Russell ( 1877 - 1957 ). Neamhspleach ar Ejnar Hertzsprung ( 1873 - 1967 ) ach ag an am ceanna leis, i 1913 , d'fhionn se an gaol idir dearbhmheid realtach is cineal speictreach, a leiritear i learaid Hertzsprung-Russell . [1]