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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



ID: 731976.0, MPI für Astronomie / Publikationen_mpia
Non-LTE line formation of Fe in late-type stars - III. 3D non-LTE analysis of metal-poor stars
Authors:Amarsi, A. M.; Lind, K.; Asplund, M.; Barklem, P. S.; Collet, R.
Date of Publication (YYYY-MM-DD):2016
Title of Journal:Monthly Notices of the Royal Astronomical Society
Volume:463
Issue / Number:2
Start Page:1518
End Page:1533
Audience:Not Specified
Abstract / Description:As one of the most important elements in astronomy, iron abundance determinations need to be as accurate as possible. We investigate the accuracy of spectroscopic iron abundance analyses using archetypal metal-poor stars. We perform detailed 3D non-LTE radiative transfer calculations based on 3D hydrodynamic STAGGER model atmospheres, and employ a new model atom that includes new quantum-mechanical neutral hydrogen collisional rate coefficients. With the exception of the red giant HD122563, we find that the 3D non-LTE models achieve Fe I/Fe II excitation and ionization balance as well as not having any trends with equivalent width to within modelling uncertainties of 0.05 dex, all without having to invoke any microturbulent broadening; for HD122563 we predict that the current best parallax-based surface gravity is overestimated by 0.5 dex. Using a 3D non-LTE analysis, we infer iron abundances from the 3D model atmospheres that are roughly 0.1 dex higher than corresponding abundances from 1D MARCS model atmospheres; these differences go in the same direction as the non-LTE effects themselves.We make available grids of departure coefficients, equivalent widths and abundance corrections, calculated on 1D MARCS model atmospheres and horizontally- and temporally-averaged 3D STAGGER model atmospheres.
Free Keywords:radiative transfer; line: formation; stars: abundances; stars: atmospheres; methods: numerical
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0035-8711 %R 10.1093/mnras/stw2077
URL:http://adsabs.harvard.edu/abs/2016MNRAS.463.1518A
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