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colloquium – Gabriele Cescutti: First results of the MINCE survey
20 Giugno 2023 @ 11:30 - 12:30
The struggle to find the most metal port stars in our Galaxy has produced an important bias in the observations and the intermediate metal-poor stars (-2.5<[Fe/H]< -1.5)
have been frequently overlooked. The missing information has consequences for the precise study of the chemical enrichment of our Galaxy, in particular for
what concerns neutron capture elements. Measuring at intermediate metallicity neutron capture elements (MINCE) aims to cover this gap, gathering
high quality spectra (high signal to noise and high resolution) of several hundred bright and metal poor stars, manly from of our Galactic halo.
In this talk, I show the results of the first sample of 42 stellar spectra for 40 different stars with the abundances of the elements up to europium. I also present
the results for the hyperfine splitting effects in two metal-poor halo stars: the profiles of the barium lines in HD 4306 agree with an s-process composition whereas
those in HD 6268 have a different profile, most likely linked to the presence of an r-process isotopic pattern. Therefore, the lines of barium of HD 6268 and HD 4306
seem to confirm the expectation that both r-process events and s-process contribution by rotating massive stars have polluted the ancient halo of our Galaxy.