Astronomia UDP

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History and evolution of the interacting Sagittarius dwarf spheroidal galaxy and its stellar populations.

The importance of chemical characterization for studying the history of the Milky Way (MW) and its accretion events is well established. However, challenges remain, especially at lower metallicities. N-capture elements carry insightful information concerning chemical evolution, but their distribution in very MW metal-poor stars shows a large dispersion in chemical space that chemical evolution models are still unable to explain (Freeman & Bland-Hawthorn, 2002). One of the possibilities may be the diversity of accreted satellites that contributed to the actual MW stellar composition. In this scenario, it is very compelling to investigate the role of the interaction between the Sagittarius dwarf spheroidal galaxy (dSph) and the MW in its structure and chemical evolution. Sgr is a dwarf satellite galaxy that orbits around the MW and it is a unique satellite, which is currently merging with ours whose core is still not destroyed. The proximity of the Sagittarius core to the Galactic bulge has made the study of the dwarf spheroidal galaxy challenging due to the contamination from Milky Way foreground stars and the high extinction level, consequently collecting data for this system is very arduous. Nevertheless, this fascinating system offers the possibility to open a window on a past but still ongoing merger event. This PhD thesis focuses on the study of the chemical evolution of this dwarf system to answer the following questions:  1) How did Sagittarius look like before being tidally disrupted by the gravitation interaction with the MW? 2) Which are the best chemical abundance ratios that allow us to trace back the evolution of this system? What story/process is being told by each element? 4) How the most informative chemical traits found for the Milky Way compare to the ones found for Sagittarius?

Type of project: PhD thesis
Status: Ongoing
Researchers: Sara Vitali, Paula Jofre
Funding source: Becas ANID, Nucleo Milenio ERIS, ESO

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