Inelastic O+H collisions and the OI 777nm solar centre-to-limb variation
| Autor: | Amarsi, A. M., Barklem, P. S., Asplund, M., Collet, R., Zatsarinny, O. |
|---|---|
| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | A&A 616, A89 (2018) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/201832770 |
| Popis: | The OI 777 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 so-called Drawin recipe, albeit with a correction factor $\mathrm{S_{H}}$ that 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 hydrodynamic stagger model 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 $\log\epsilon_{\mathrm{O}}=8.69\pm0.03$ from the triplet alone, strengthening the case for a low solar oxygen abundance. Comment: 13 pages, 8 figures; published in Astronomy & Astrophysics |
| Databáze: | arXiv |
| Externí odkaz: |
|