标题： 具有不同X射线性质的早期类型星系中恒星群体的均匀性 显示英文标题

标题： Homogeneity of Stellar Populations in Early-Type Galaxies with Different X-ray Properties

摘要： 我们发现，早型星系的恒星种群是均质的，颜色和Mg2指数没有显著差异，尽管存在X射线延展型早型星系与X射线紧致型早型星系之间的二分法。 由于X射线性质反映了可能的引力结构以及因此的星系形成过程，恒星种群的均质性表明，早型星系中的恒星形成发生在势结构分化之前的时代。 显示英文摘要

摘要： We have found the stellar populations of early-type galaxies are homogeneous with no significant difference in color or Mg2 index, despite the dichotomy between X-ray extended early-type galaxies and X-ray compact ones. Since the X-ray properties reflect the potential gravitational structure and hence the process of galaxy formation, the homogeneity of the stellar populations implies that the formation of stars in early-type galaxies predat es the epoch when the dichotomy of the potential structure was established.