Talk Title: A metal rich neighbour: chemical patterns in the Sagittarius Dwarf Spheriodal Galaxy
Abstract: We present detailed abundance analysis for 12 red giants in the Sagittarius Dwarf Spheroidal Galaxy (Sgr dSph) and 6 in the associated globular cluster Terzan 7, obtained from VLT-UVES high resolution spectra. This dwarf, the closest neighbour of the Milky Way, is on the verge of being tidally disrupted by our Galaxy, and is leaving a well defined stream of stars in the halo along its orbit. Currently, strong clues exist that some of the MWG halo globular clusters have been stripped from the Sgr dSph. We detected a young population (age < 2 GYr), in fact dominant in our sample, with solar iron abundance and a characteristic alpha-element underenhancement extending to the lowest observed metallicities. The interpretation of this results, points toward a scenario of slow or bursting star formation history, triggered by the crossings of the galactic disc experienced by the dSph once in a gigayear along its orbit. Most strikingly, the metal rich population we observed puts the Sgr dSph on the metal rich - alpha deficient extreme of an abundance pattern along wich the local group's dSph appear to lay, significantly separated from the Milky Way's disc population, but strongly similar to the one characterizing the so-called Damped Lyman Alpha (DLA) systems.
(Authors: L. Sbordone, P. Bonifacio, G. Marconi, R. Buonanno, L. Pasquini)
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