paper

Formation of omega Centauri from an ancient nucleated dwarf galaxy in the young Galactic disc

arXiv:astro-ph/0310348 · doi:10.1046/j.1365-2966.2003.07275.x

Abstract

We first present a self-consistent dynamical model in which Cen is formed from an ancient nucleated dwarf galaxy merging with the first generation of the Galactic thin disc in a retrograde manner with respect to the Galactic rotation. Our numerical simulations demonstrate that during merging between the Galaxy and the Cen's host dwarf with -14 mag and its nucleus mass of , the outer stellar envelope of the dwarf is nearly completely stripped whereas the central nucleus can survive from the tidal stripping because of its compactness. The developed naked nucleus has a very bound retrograde orbit around the young Galactic disc, as observed for Cen, with its apocenter and pericenter distances of 8 kpc and 1 kpc, respectively. The Galactic tidal force can induce radial inflow of gas to the dwarf's center and consequently triggers moderately strong nuclear starbursts in a repetitive manner. This result implies that efficient nuclear chemical enrichment resulting from the later starbursts can be closely associated with the origin of the observed relatively young and metal-rich stars in Cen. Dynamical heating by the Cen's host can transform the young thin disc into the thick disc during merging.

5 pages, 5 figures, accepted in MNRAS (Pink page)

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