Stellar Objects of Extragalactic Origin in the Galactic Halo

TL;DR

This study identifies and analyzes extragalactic origin objects in the Galactic halo, revealing their chemical, physical, and kinematic properties, and how these relate to galaxy formation and evolution.

Contribution

It provides new insights into the properties and origins of extragalactic objects in the Galactic halo, highlighting their chemical differences and formation history.

Findings

Majority of metal-poor stellar objects are of extragalactic origin.

Masses of accreted globular clusters decrease with distance from the Galactic center.

Accreted stars show decreasing magnesium abundances with larger, more inclined orbits.

Abstract

We identified globular clusters and field stars of extragalactic origin and investigated their chemical, physical, and kinematical properties. This objects as supposed was captured by the Galaxy at different times from debris of the dwarf satellite galaxies disrupted by its tidal forces. The results are follows. (1) The majorities of metal-poor stellar objects in the Galaxy have an extragalactic origin. (2) The masses of the accreted globular clusters decrease with the removal from the center and the plane of the Galaxy. (3) The relative abundances of chemical elements in the accreted and genetically connected stars are essentially distinguished. (4) The accreted field stars demonstrate the decrease of the relative magnesium abundanses with an increase in sizes and inclinations of their orbits. (5) The stars of the Centaurus moving group were born from the matter, in which star formation rate was considerably lower than in the early Galaxy. On the base of these properties was made a conclusion that with the decrease of the masses of the dwarf galaxies in them simultaneously decrease the average masses of globular clusters and the maximum masses of supernova SNe II. Namely latter fact leads to the decrease of the relative abundances of \alpha-elements in their metal-poor stars.