Atomic processes in stellar atmospheres: towards high-accuracy stellar abundances for Galactic archeology

by Paul Barklem (Uppsala University)

Monday 21 Nov 2016, 10:00 → 11:00 Europe/Stockholm

FA 31

The European Gaia-satellite mission will provide us with positions and velocities of around a billion stars in our Galaxy. This will lead to a paradigm shift in both our understanding of the Milky Way as a galaxy as well as how we do Galactic research. To fully unravel the formation of the Milky Way (often called Galactic archeology), as well for other problems in astrophysics, high-accuracy stellar chemical abundances are required. This requires analysis of stellar spectra beyond the classical approximations of 1D atmospheric models and local thermodynamic equilibrium (LTE). Modelling beyond LTE has long been hampered by a lack of data for atomic collision processes due to electrons and hydrogen atoms. In this talk I describe the significant progress that is being made on these two fronts. In particular I will present results from an asymptotic approach for calculations of inelastic processes due to hydrogen atom impacts on a large numbers of elements. I will also describe recent close-coupling calculations of inelastic processes in atoms due to electron impacts. Some examples of the astrophysical impact of the results will be shown.