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Population gradients in dwarf spheroidal galaxies KKs 3 and ESO 269-66

Published online by Cambridge University Press:  30 October 2019

M. E. Sharina
Affiliation:
Special Astrophysical Observatory, Russian Academy of Sciences, N. Arkhyz, KChR 369167, Russia emails: sme@sao.ru, lidia@sao.ru, dim@sao.ru
L. N. Makarova
Affiliation:
Special Astrophysical Observatory, Russian Academy of Sciences, N. Arkhyz, KChR 369167, Russia emails: sme@sao.ru, lidia@sao.ru, dim@sao.ru
D. I. Makarov
Affiliation:
Special Astrophysical Observatory, Russian Academy of Sciences, N. Arkhyz, KChR 369167, Russia emails: sme@sao.ru, lidia@sao.ru, dim@sao.ru
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Abstract

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We compare the properties of stellar populations for globular clusters (GCs) and field stars in two dwarf spheroidal galaxies (dSphs): ESO269-66, a close neighbour of NGC5128, and KKs3, one of the few isolated dSphs within 10 Mpc. We analyse the surface density profiles of low and high metallicity (blue and red) stars in two galaxies using the Sersic law. We argue that 1) the density profiles of red stars are steeper than those of blue stars, which evidences in favour of the metallicity and age gradients in dSphs; 2) globular clusters in KKs3 and ESO 269-66 contain 4 and 40 percent of all stars with [Fe / H] ~ 1.6 dex and the age of 12 Gyr, correspondingly. Therefore, GCs are relics of the first powerful star-forming bursts in the central regions of the galaxies. KKs 3 has lost a smaller percentage of old low-metallicity stars than ESO269-66, probably, thanks to its isolation.

Type
Contributed Papers
Copyright
© International Astronomical Union 2019 

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