Volume 624, April 2019
|Number of page(s)||14|
|Published online||19 April 2019|
3D non-LTE line formation of neutral carbon in the Sun
Max Planck Institute für Astronomy,
2 Theoretical Astrophysics, Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden
3 Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark
4 Centre Spatial de Liège, Université de Liége, Avenue Pré Aily, 4031 Angleur-Liège, Belgium
5 Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Allée du 6 août, 17, B5C, 4000 Liège, Belgium
6 Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611, Australia
Accepted: 20 March 2019
Carbon abundances in late-type stars are important in a variety of astrophysical contexts. However C I lines, one of the main abundance diagnostics, are sensitive to departures from local thermodynamic equilibrium (LTE). We present a model atom for non-LTE analyses of C I lines, that uses a new, physically-motivated recipe for the rates of neutral hydrogen impact excitation. We analyse C I lines in the solar spectrum, employing a three-dimensional (3D) hydrodynamic model solar atmosphere and 3D non-LTE radiative transfer. We find negative non-LTE abundance corrections for C I lines in the solar photosphere, in accordance with previous studies, reaching up to around 0.1 dex in the disk-integrated flux. We also present the first fully consistent 3D non-LTE solar carbon abundance determination: we infer log ɛC = 8.44 ± 0.02, in good agreement with the current standard value. Our models reproduce the observed solar centre-to-limb variations of various C I lines, without any adjustments to the rates of neutral hydrogen impact excitation, suggesting that the proposed recipe may be a solution to the long-standing problem of how to reliably model inelastic collisions with neutral hydrogen in late-type stellar atmospheres.
Key words: atomic data / radiative transfer / line: formation / Sun: abundances / Sun: photosphere
© A. M. Amarsi et al. 2019
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Open Access funding provided by Max Planck Society.
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