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arXiv · 1709.08619

Galactic evolution of Copper in the light of NLTE computations

S. Andrievsky·P. Bonifacio·E. Caffau·S. Korotin·M. Spite·F. Spite·L. Sbordone·A. V. Zhukova
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Abstract

We have developed a model atom for Cu with which we perform statistical equilibrium computations that allow us to compute the line formation of Cu I lines in stellar atmospheres without assuming Local Thermodynamic Equilibrium (LTE). We validate this model atom by reproducing the observed line profiles of the Sun, Procyon and eleven metal-poor stars. Our sample of stars includes both dwarfs and giants. Over a wide range of stellar parameters we obtain excellent agreement among different Cu I lines. The eleven metal-poor stars have iron abundances in the range -4.2 <= [Fe/H] <= -1.4, the weighted mean of the [Cu/Fe] ratios is -0.22 dex, with a scatter of -0.15 dex. This is very different from the results from LTE analysis (the difference between NLTE and LTE abundances reaches 1 dex) and in spite of the small size of our sample it prompts for a revision of the Galactic evolution of Cu.

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S. Andrievsky, P. Bonifacio, E. Caffau, S. Korotin, M. Spite, F. Spite, L. Sbordone, A. V. Zhukova. 2017-09-25. Galactic evolution of Copper in the light of NLTE computations. https://doi.org/10.1093/mnras%2Fstx2526

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