Galactic evolution of copper in the light of NLTE computations. Issue 3 (27th September 2017)

• Record Type: Journal Article
• Authors: Andrievsky, S.; Bonifacio, P.; Caffau, E.; Korotin, S.; Spite, M.; Spite, F.; Sbordone, L.; Zhukova, A. V.
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 473:Issue 3(2018)
• Page Start: 3377
• Page End: 3384
• Publication Date: 2017-09-27
• Subjects: line: formation -- line: profiles -- radiative transfer -- stars: abundances -- stars: atmospheres -- Galaxy: evolution; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stx2526
• Languages: English
• ISSNs: 0035-8711

Abstract

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 11 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 11 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.