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Related papers: Non-LTE Equivalent Widths for NII with Error Estim…

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We test our knowledge of the atomic opacity in the solar UV spectrum. Using the atomic data compiled in Paper I from modern, publicly available, databases, we perform calculations that are confronted with space-based observations of the…

Astrophysics · Physics 2009-11-07 C. Allende Prieto , I. Hubeny , D. L. Lambert

A five-dimensional interpolation method and corresponding computer program are developed for using published calculations to determine the non-LTE correction {\Delta\}NLTE to the lithium abundance log{\epsilon}(Li) derived from the Li I…

Solar and Stellar Astrophysics · Physics 2017-10-18 L. S. Lyubimkov , D. V. Petrov

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

We determine Mg abundances in 6 Gaia benchmark stars using theoretical one-dimensional (1D) hydrostatic model atmospheres, as well as temporally- and spatially-averaged 3D model atmospheres (<3D>). The stars cover a range of Teff from 4700…

Solar and Stellar Astrophysics · Physics 2017-09-27 Maria Bergemann , Remo Collet , Anish M. Amarsi , Mikhail Kovalev , Gregory Ruchti , Zazralt Magic

It is well known that cool star atmospheres depart from local thermodynamic equilibrium (LTE). Accurate abundance determination requires taking those effects into account, but the necessary non-LTE calculations are often lacking. Our goal…

Solar and Stellar Astrophysics · Physics 2022-09-14 K. Lind , T. Nordlander , A. Wehrhahn , M. Montelius , Y. Osorio , P. S. Barklem , M. Afsar , C. Sneden , C. Kobayashi

Non-local thermodynamical equilibrium (NLTE) line formation for neutral and singly-ionized calcium is considered through a range of spectral types when the Ca abundance varies from the solar value down to [Ca/H] = -5. Departures from LTE…

Astrophysics · Physics 2009-11-11 L. Mashonkina , A. J. Korn , N. Przybilla

We present non-Local Thermodynamic Equilibrium (non-LTE) calculations for neutral carbon spectral line formation, carried out for a grid of model atmospheres covering the range of late-type stars. The results of our detailed calculations…

Astrophysics · Physics 2015-06-24 Damian Fabbian , Martin Asplund , Mats Carlsson , Dan Kiselman

We report the detection of an Al II line at 2669.155 Angstroms in 11 metal-poor stars, using ultraviolet spectra obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. We derive Al abundances from this…

Solar and Stellar Astrophysics · Physics 2021-05-19 Ian U. Roederer , James E. Lawler

Non-LTE calculations for Mg I in red supergiant stellar atmospheres are presented to investigate the importance of non-LTE for the formation of Mg I lines in the NIR J-band. Recent work using medium resolution spectroscopy of atomic lines…

Solar and Stellar Astrophysics · Physics 2015-05-27 Maria Bergemann , Rolf-Peter Kudritzki , Zach Gazak , Ben Davies , Bertrand Plez

Extensive statistical-equilibrium calculations on neutral sulfur and zinc were carried out, in order to investigate how the non-LTE effect plays a role in the determination of S and Zn abundances in F, G, and K stars. Having checked on the…

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…

Solar and Stellar Astrophysics · Physics 2019-04-24 A. M. Amarsi , P. S. Barklem , R. Collet , N. Grevesse , M. Asplund

A comprehensive model atom was constructed for C I using the most up-to-date atomic data. We evaluated non-local thermodynamical equilibrium (NLTE) line formation for neutral carbon in classical 1D models representing atmospheres of…

Solar and Stellar Astrophysics · Physics 2015-09-09 S. A. Alexeeva , L. I. Mashonkina

We describe the first results from our project aimed at large-scale calculations of NLTE abundance corrections for important astrophysical atoms and ions. In this paper, the focus is on Fe which is a proxy of stellar metallicity and is…

Solar and Stellar Astrophysics · Physics 2015-05-30 Maria Bergemann , Karin Lind , Remo Collet , Martin Asplund

We present accurate methods of abundance determination based on the non-local thermodynamic equilibrium (NLTE) line formation for carbon, oxygen, calcium, titanium, and iron in the atmospheres of BAF-type stars. For C I-II, O I, Ca I-II,…

Solar and Stellar Astrophysics · Physics 2018-08-22 Tatyana Sitnova , Tatyana Ryabchikova , Sofya Alexeeva , Lyudmila Mashonkina

With the goal of producing a reliable set of model atoms and singly-ionized ions for use in building NLTE model atmospheres, we have combined measured energy levels, critically-compiled line transition probabilities, and resonance-averaged…

Astrophysics · Physics 2009-11-07 C. Allende Prieto , D. L. Lambert , I. Hubeny , T. Lanz

Our ability to model the shapes and strengths of iron lines in the solar spectrum is a critical test of the accuracy of the solar iron abundance, which sets the absolute zero-point of all stellar metallicities. We use an extensive 463-level…

Solar and Stellar Astrophysics · Physics 2017-05-31 K. Lind , A. M. Amarsi , M. Asplund , P. S. Barklem , M. Bautista , M. Bergemann , R. Collet , D. Kiselman , J. Leenaarts , T. M. D. Pereira

We present a new model atom of Zn I-II based on the most up-to-date photoionisation cross-sections, electron-impact excitation rates, and rate coefficients for the Zn I + H I and Zn II + H- collisions. The latter were calculated using the…

Solar and Stellar Astrophysics · Physics 2022-07-20 T. M. Sitnova , S. A. Yakovleva , A. K. Belyaev , L. I. Mashonkina

In this work we analyze the beryllium-iron chemical diagram from the point of view of non-LTE effects. Be abundances were re-calculated by considering non-LTE corrections in ionization equilibrium (logg) and Fe abundances ([Fe/H]). These…

Astrophysics · Physics 2007-05-23 T. P. Idiart , F. Thevenin

The non-local thermodynamic equilibrium (NLTE) line formation of neutral boron in the atmospheres of cool stars are investigated. Our results confirm that NLTE effects for the B I resonance lines, which are due to a combination of…

Solar and Stellar Astrophysics · Physics 2010-04-07 Kefeng Tan , Jianrong Shi , Gang Zhao

We investigate NLTE effects for magnesium and calcium in the atmospheres of late-type giant and supergiant stars. The aim of this paper is to provide a grid of NLTE/LTE equivalent width ratios W/W* of Mg and Ca lines for the following range…

Solar and Stellar Astrophysics · Physics 2015-05-30 Thibault Merle , Frédéric Thévenin , Bernard Pichon , Lionel Bigot