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We investigate the non-local thermodynamic equilibrium (NLTE) analysis for \ion{Cu}{1} lines with the updated model atom that includes quantum-mechanical rate coefficients of Cu\,$+$\,H and Cu$^+$\,$+$\,H$^-$ inelastic collisions from the…

Solar and Stellar Astrophysics · Physics 2022-08-31 Xiaodong Xu , Jianrong Shi , Xiaofeng Wang

The influence of inelastic hydrogen atom collisions on non-LTE spectral line formation has been, and remains to be, a significant source of uncertainty for stellar abundance analyses, due to the difficulty in obtaining accurate data for…

Solar and Stellar Astrophysics · Physics 2015-05-27 P. S. Barklem , A. K. Belyaev , M. Guitou , N. Feautrier , F. X. Gadea , A. Spielfiedel

We perform the non-local thermodynamic equilibrium (NLTE) calculations for Ca I-II with the updated model atom that includes new quantum-mechanical rate coefficients for Ca I + H I collisions from two recent studies, that is, by Barklem and…

Solar and Stellar Astrophysics · Physics 2017-09-13 L. Mashonkina , T. Sitnova , A. K. Belyaev

We performed the non-local thermodynamic equilibrium (non-LTE) calculations for Ti I-II with the updated model atom that includes quantum-mechanical rate coefficients for inelastic collisions with hydrogen atoms. We have calculated for the…

Solar and Stellar Astrophysics · Physics 2020-05-19 T. M. Sitnova , S. A. Yakovleva , A. K. Belyaev , L. I. Mashonkina

We present the non-local thermodynamic equilibrium (non-LTE) calculations for O I with the updated model atom that includes quantum-mechanical rate coefficients for O I + H I inelastic collisions from the recent study of Barklem (2018). The…

Solar and Stellar Astrophysics · Physics 2018-08-23 Tatyana Sitnova , Lyudmila Mashonkina

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…

Solar and Stellar Astrophysics · Physics 2018-10-30 A. M. Amarsi , P. S. Barklem , M. Asplund , R. Collet , O. Zatsarinny

Neutral sodium is a minority species in the atmospheres of late-type stars, and line formation in local thermodynamic equilibrium (LTE) is often a poor assumption, in particular for strong lines. We present an extensive grid of non-LTE…

Solar and Stellar Astrophysics · Physics 2015-05-27 K. Lind , M. Asplund , P. S. Barklem , A. K. Belyaev

The treatment of the inelastic collisions with electrons and hydrogen atoms are the main source of uncertainties in non-Local Thermodynamic Equilibrium (LTE) spectral line computations. We report, in this research note, quantum mechanical…

Solar and Stellar Astrophysics · Physics 2015-05-27 T. Merle , F. Thévenin , O. Zatsarinny

Magnesium abundances of cool stars with different metallicities are important for understanding the galactic chemical evolution. This study tests atomic data used in stellar magnesium abundance analyses. We evaluate non-local…

Solar and Stellar Astrophysics · Physics 2015-06-12 Lyudmila Mashonkina

The non-LTE line formation for Al I and Si I was calculated with model atmospheres corresponding to F-G-K type stars of different metallicity. To account for inelastic collisions with H I, for the first time we applied the cross sections…

Solar and Stellar Astrophysics · Physics 2016-06-22 Lyudmila Mashonkina , Andrey K. Belyaev , Jianrong Shi

The new version of TLUSTY allows for the calculation of restricted NLTE in cool stars using pre-calculated opacity tables. We demonstrate that TLUSTY gives consistent results with MULTI, a well-tested code for NLTE in cool stars. We use…

Solar and Stellar Astrophysics · Physics 2020-05-20 Yeisson Osorio , Carlos Allende-Prieto , Ivan Hubeny , Szabolcs Meszaros , Matthew Shetrone

In the aim of determining accurate iron abundances in stars, this work is meant to empirically calibrate H-collision cross-sections with iron, where no quantum mechanical calculations have been published yet. Thus, a new iron model atom has…

Solar and Stellar Astrophysics · Physics 2016-09-30 Rana Ezzeddine , Thibault Merle , Bertrand Plez

Aiming at testing the validity of our magnesium atomic model and investigating the effects of non-local thermodynamical equilibrium (NLTE) on the formation of the H-band neutral magnesium lines, we derive the differential Mg abundances from…

Solar and Stellar Astrophysics · Physics 2017-01-25 Junbo Zhang , Jianrong Shi , Kaike Pan , Carlos Allende Prieto , Chao Liu

(*** abridged ***) Context: The wings of Balmer lines are often used as effective temperature diagnostics for late-type stars under the assumption they form in local thermodynamic equilibrium. Aims: Our goal is to investigate the non-LTE…

Astrophysics · Physics 2009-11-13 P. S. Barklem

We construct a comprehensive model atom for TiI-II using more than 3600 measured and predicted energy levels of TiI and 1800 energy levels of TiII, and quantum mechanical photoionisation cross-sections. Non-local thermodynamical equilibrium…

Solar and Stellar Astrophysics · Physics 2016-07-27 T. M. Sitnova , L. I. Mashonkina , T. A. Ryabchikova

Rate coefficients for inelastic collisions between Li and H atoms covering all transitions between the asymptotic states Li(2s,2p,3s,3p,3d,4s,4p,4d,4f)+H(1s) and Li^+ +H^- are presented for the temperature range 2000-8000 K based on recent…

Astrophysics · Physics 2009-11-10 P. S. Barklem , A. K. Belyaev , M. Asplund

Iron plays a crucial role in studies of late-type stars. In their atmospheres, Fe I is the minority species and its lines are subject to the departures from LTE. In contrast, one believes that LTE is a realistic approximation for Fe II…

Solar and Stellar Astrophysics · Physics 2019-10-23 Lyudmila Mashonkina , Tatyana Sitnova , Svetlana A. Yakovleva , Andrey K. Belyaev

Manganese (Mn) is a key Fe-group elements, commonly employed in stellar population and nucleosynthesis studies to explore the role of SN Ia. We have developed a new non-local thermodynamic equilibrium (NLTE) model of Mn, including new…

The influence of the uncertainties in the rate coefficient data for electron-impact excitation and ionization on non-LTE Li line formation in cool stellar atmospheres is investigated. We examine the electron collision data used in previous…

Solar and Stellar Astrophysics · Physics 2015-05-27 Y. Osorio , P. S. Barklem , K. Lind , M. Asplund

We evaluate the effect of variations in the electron-impact excitation cross sections on the non-LTE line formation for hydrogen in early-type stars. While the Balmer lines are basically unaffected by the choice of atomic data, the Brackett…

Astrophysics · Physics 2009-11-11 Norbert Przybilla , Keith Butler
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