AustralieFrV1, Main, Exploration, bibRecord, 00A660

Effects of line-blocking on the non-LTE Fe I spectral line formation

Identifieur interne : 00A660 ( Main/Exploration ); précédent : 00A659; suivant : 00A661

Effects of line-blocking on the non-LTE Fe I spectral line formation

Auteurs : R. Collet [Suède] ; M. Asplund [Australie] ; F. Thevenin [France]

Source :

Astronomy and astrophysics : (Berlin. Print) [ 0004-6361 ] ; 2005.

RBID : Pascal:05-0455145

Descripteurs français

Pascal (Inist)
- Ecart équilibre thermodynamique local, Formation raie, Opacité, Equilibre statistique, Atmosphère stellaire, Modèle stellaire, Modèle atmosphère, Métallicité, Equilibre thermodynamique local, Déséquilibre thermodynamique, Abondance stellaire, Correction, Incertitude, Etoile pauvre en métal, Collision inélastique, Etat fondamental, Soleil.

English descriptors

KwdEn :
- Atmosphere model, Corrections, Ground states, Inelastic collision, LTE, Line formation, Metal-poor stars, Metallicity, Non-LTE, Opacity, Star models, Statistical equilibrium, Stellar abundance, Stellar atmospheres, Sun, Thermodynamic non equilibrium, Uncertainty.

Abstract

The effects of background line opacity (line-blocking) in statistical equilibrium calculations for Fe in late-type stellar atmospheres have been investigated using an extensive and up-to-date model atom with radiative data primarily from the IRON Project. The background metal line opacities have been computed using data from the MARCS stellar model atmospheres. While accounting for this line opacity is important at solar metallicity, the differences between calculations including and excluding line-blocking at low metallicity are insignificant for the non-local thermodynamic equilibrium (non-LTE) abundance corrections for FeI lines. The line-blocking has no impact on the non-LTE effects of Fe II lines. The dominant uncertainty in Fe non-LTE calculations for metal-poor stars is still the treatment of the inelastic H I collisions, which here have been included using scaling factors to the classical Drawin formalism, and whether or not thermalisation of the high FeI levels to Fe II ground state should be enforced. Without such thermalisation, the Fe I non-LTE abundance corrections are substantial in metal-poor stars: about 0.3 dex with efficient (i.e. Drawin-like) Hi collisions and ≤0.5 dex without. Without both thermalisation and HI collisions, even Fell lines show significant non-LTE effects in such stars.

Affiliations:

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Le document en format XML

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<term>Atmosphère stellaire</term>
<term>Modèle stellaire</term>
<term>Modèle atmosphère</term>
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<term>Déséquilibre thermodynamique</term>
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<front><div type="abstract" xml:lang="en">The effects of background line opacity (line-blocking) in statistical equilibrium calculations for Fe in late-type stellar atmospheres have been investigated using an extensive and up-to-date model atom with radiative data primarily from the IRON Project. The background metal line opacities have been computed using data from the MARCS stellar model atmospheres. While accounting for this line opacity is important at solar metallicity, the differences between calculations including and excluding line-blocking at low metallicity are insignificant for the non-local thermodynamic equilibrium (non-LTE) abundance corrections for FeI lines. The line-blocking has no impact on the non-LTE effects of Fe II lines. The dominant uncertainty in Fe non-LTE calculations for metal-poor stars is still the treatment of the inelastic H I collisions, which here have been included using scaling factors to the classical Drawin formalism, and whether or not thermalisation of the high FeI levels to Fe II ground state should be enforced. Without such thermalisation, the Fe I non-LTE abundance corrections are substantial in metal-poor stars: about 0.3 dex with efficient (i.e. Drawin-like) Hi collisions and ≤0.5 dex without. Without both thermalisation and HI collisions, even Fell lines show significant non-LTE effects in such stars.</div>
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Effects of line-blocking on the non-LTE Fe I spectral line formation

Effects of line-blocking on the non-LTE Fe I spectral line formation

Source :

Descripteurs français

English descriptors

Abstract

Links toward previous steps (curation, corpus...)

Le document en format XML

Pour manipuler ce document sous Unix (Dilib)

Pour mettre un lien sur cette page dans le réseau Wicri