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Paper: The Stellar Populations of Ultra Faint Dwarf Galaxies
Volume: 458, Galactic Archaeology: Near-Field Cosmology and the Formation of the Milky Way
Page: 283
Authors: Okamoto, S.; Arimoto, N.
Abstract: We present the deep colour-magnitude diagrams (CMDs) of Galactic dwarf spheroidal (dSph) galaxies, including six ultra faint dwarf (UFD) galaxies, based on the images taken by Subaru/Suprime-Cam. The resulting CMDs show that the brighter galaxies have relatively younger populations than those of fainter ones. In the brighter dSphs, the younger populations are more spatially concentrated to the galaxy center than the old stars, indicating that the star formation in the central region continued for at least a few Gyrs, consistent with the different spatial distributions of red and blue HB stars. On the other hand, the CMDs of the faintest satellites show a single epoch of star formation as a metal-poor Galactic globular cluster. This result indicates that the gases in the progenitors of UFDs were removed more effectively than those of brighter dSphs at an occurrence of their initial star formation. This is reasonable if the UFD progenitors were likely to belong to the less massive halos than those of brighter dSphs.
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