Globular clusters and dwarf spheroidal galaxies of the outer galactic halo: On the putative scenario of their formation

Abstract

Abstract According to observational data, some of the Galactic globular clusters (GCs) belonging to the outer halo form a separate subsystem of globulars: they are mainly on retrograde orbits, show younger ages than other GCs of the outer halo, etc. Moreover, there is evidence suggestive of a common, accretive origin of at least some of both these GCs and the dwarf spheroidal galaxies, satellites of the Milky Way. I discuss a scenario which, if real, would explain the origin and several peculiar characteristics of the objects under consideration. It is based on two fairly realistic assumptions: (i) the first burst of star formation in which a bulk of the population II formed in the Galaxy and M 31, led to a considerable mass loss, up to half mass of each protogalaxy; (ii) the Milky Way together with M 31 have formed a binary galactic system since the earliest epoch. Hence I suggest that just after (or during) the formation of their spheroids the Galaxy and M 31 mutually exchanged gas by its transfer, in p...