Homogeneity of Stellar Populations in Early-type Galaxies with Different X-ray Properties
نویسندگان
چکیده
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 predates the epoch when the dichotomy of the potential structure was established. Subject headings: galaxies: elliptical and lenticular — galaxies: formation — galaxies: evolution — galaxies: stellar content —galaxies: ISM
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