2017A&A...607A..75N


Query : 2017A&A...607A..75N

2017A&A...607A..75N - Astronomy and Astrophysics, volume 607A, 75-75 (2017/11-1)

Non-LTE aluminium abundances in late-type stars.

NORDLANDER T. and LIND K.

Abstract (from CDS):

Aims. Aluminium plays a key role in studies of the chemical enrichment of the Galaxy and of globular clusters. However, strong deviations from LTE (non-LTE) are known to significantly affect the inferred abundances in giant and metal-poor stars.
Methods. We present non-local thermodynamic equilibrium (NLTE) modeling of aluminium using recent and accurate atomic data, in particular utilizing new transition rates for collisions with hydrogen atoms, without the need for any astrophysically calibrated parameters. For the first time, we perform 3D NLTE modeling of aluminium lines in the solar spectrum. We also compute and make available extensive grids of abundance corrections for lines in the optical and near-infrared using one-dimensional model atmospheres, and apply grids of precomputed departure coefficients to direct line synthesis for a set of benchmark stars with accurately known stellar parameters.
Results. Our 3D NLTE modeling of the solar spectrum reproduces observed center-to-limb variations in the solar spectrum of the 7835Å line as well as the mid-infrared photospheric emission line at 12.33µm. We infer a 3D NLTE solar photospheric abundance of A(Al)=6.43±0.03, in exact agreement with the meteoritic abundance. We find that abundance corrections vary rapidly with stellar parameters; for the 3961Å resonance line, corrections are positive and may be as large as +1dex, while corrections for subordinate lines generally have positive sign for warm stars but negative for cool stars. Our modeling reproduces the observed line profiles of benchmark K-giants, and we find abundance corrections as large as -0.3dex for Arcturus. Our analyses of four metal-poor benchmark stars yield consistent abundances between the 3961Å resonance line and lines in the UV, optical and near-infrared regions. Finally, we discuss implications for the galactic chemical evolution of aluminium.

Abstract Copyright: © ESO, 2017

Journal keyword(s): stars: abundances - stars: atmospheres - techniques: spectroscopic - line: formation - line: formation

Simbad objects: 8

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Number of rows : 8
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 UCAC4 115-002803 Pe* 03 13 00.3747928560 -67 08 39.336144504   15.442 14.753 14.639   CEMP-no 111 0
2 HD 22879 Pe* 03 40 22.0652879951 -03 13 01.124265616 7.146 7.222 6.667 6.346 6.016 G0VmF2 500 0
3 * bet Gem PM* 07 45 18.94987 +28 01 34.3160 3.00 2.14 1.14 0.39 -0.11 K0IIIb 1105 2
4 HD 84937 Pe* 09 48 56.0992891997 +13 44 39.326709913 8.49 8.68 8.32 7.97 7.70 F8Vm-5 799 0
5 HD 122563 Pe* 14 02 31.8455084952 +09 41 09.944391876 7.47 7.10 6.19 5.37 4.79 G8:III:Fe-5 857 0
6 * alf Boo RG* 14 15 39.67207 +19 10 56.6730 2.46 1.18 -0.05 -1.03 -1.68 K1.5IIIFe-0.5 2331 1
7 HD 140283 Pe* 15 43 03.0971190219 -10 56 00.595693188 7.508 7.711 7.212 6.63 8.21 F9VkA5mA1 943 0
8 NAME Galactic Bulge reg ~ ~           ~ 4332 0

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