nucleated dwarf galaxy 有核矮星系
number density profile 数密度轮廓
numbered asteroid 编号小行星
oblique pulsator 斜脉动星
observational cosmology 观测宇宙学
observational dispersion 观测弥散度
observational material 观测资料
observing season 观测季
occultation band 掩带
O-Ne-Mg white dwarf 氧氖镁白矮星