Galactic evolution of Copper in the light of NLTE computations

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.

To be published in MNRAS

References in corpus (8)

• New Grids of ATLAS9 Model Atmospheres
• Gaia-ESO Survey: The analysis of high-resolution UVES spectra of FGK-type stars
• The elemental composition of the Sun III. The heavy elements Cu to Th
• New Extremely Metal-Poor Stars in the Galactic Halo
• New Detections of Arsenic, Selenium, and Other Heavy Elements in Two Metal-Poor Stars
• Chemical abundances in giants stars of the tidally disrupted globular cluster NGC 6712 from high-resolution infrared spectroscopy
• Non-LTE analysis of neutral copper in the late-type metal-poor stars
• Abundances of the light elements from UV (HST) and red (ESO) spectra in the very old star HD 84937

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• NLTE Analysis of Copper Abundances in the Galactic Bulge Stars
• The effect of hyperfine splitting on Stark broadening for three blue-green Cu I lines in laser-induced plasma
• The Impact of Inelastic Collisions with Hydrogen on NLTE Copper Abundances in Metal-Poor Stars
• The origin of elements: the need for UV spectra
• Purveyors of fine halos III. Chemical abundance analysis of a potential omega Cen associate
• On the Chemical Composition of the Evolved Very Bright Metal-Poor Star HD 1936