Seminario DAS: "Sulfur as a tracer of the chemical evolution of the Milky Way"

Speaker: Dr. Francesca Lucertini
Affiliation: ESO – European Southern Observatory

Abstract: The alpha-elements are the proof of the chemical enrichment delay due to Supernovae type-II. When compared with iron, they can be used as cosmic clocks for placing constraints on both stellar nucleosynthesis and galaxy's formation history. 

Sulfur is the outcast alpha-element. Indeed, its analysis is often skipped in favor of the other alpha-elements, which are less complicated to measure. For this reason, so far, the behavior of sulfur has been mainly investigated in Galactic stellar atmospheres and a few globular clusters. Among the alpha-elements, sulfur is the proxy for high-redshift systems. Its volatile nature allows to directly compare sulfur abundances measured in local stars and gaseous phase in the far Universe, as extragalactic HII regions and Damped Ly-alpha systems (DLA). This kind of studies are relevant for the understanding of galaxy's formation and the evolution, since DLA are the progenitors of dwarf galaxies (i.e. the Milky Way building blocks). However, the Sculptor dwarf spheroidal galaxy is the only extragalactic system for which sulfur abundances has been measured from stellar atmospheres.  

This talk aims to show up new outcomes concerning the behavior of sulfur in the Milky Way major components (bulge, disk, halo and stellar clusters).  Exploiting sulfur as tracer of the chemical evolution of our Galaxy, clues on the Milky Way's formation and a reliable dataset to compare local and distant systems will be provided.