文章基本信息

标题：Inelastic O+H collisions and the O  I 777 nm solar centre-to-limb variation
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作者：A. M. Amarsi ; P. S. Barklem ; M. Asplund 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2018
卷号：616
DOI：10.1051/0004-6361/201832770
语种：English
出版社：EDP Sciences
摘要：The O I777 nm triplet is a key diagnostic of oxygen abundances in the atmospheres of FGK-type stars; however, it is sensitive to departures from local thermodynamic equilibrium (LTE). The accuracy of non-LTE line formation calculations has hitherto been limited by errors in the inelastic O+H collisional rate coefficients; several recent studies have used the Drawin recipe, albeit with a correction factorSHthat is calibrated to the solar centre-to-limb variation of the triplet. We present a new model oxygen atom that incorporates inelastic O+H collisional rate coefficients using an asymptotic two-electron model based on linear combinations of atomic orbitals, combined with a free electron model based on the impulse approximation. Using a 3D hydrodynamicSTAGGERmodel solar atmosphere and 3D non-LTE line formation calculations, we demonstrate that this physically motivated approach is able to reproduce the solar centre-to-limb variation of the triplet to 0.02 dex, without any calibration of the inelastic collisional rate coefficients or other free parameters. We infer log ϵO= 8.69 ± 0.03 from the triplet alone, strengthening the case for a low solar oxygen abundance.
关键词：Key wordsenatomic dataradiative transferline: formationSun: atmosphereSun: abundancesmethods: numerical