Sodium abundances in nearby disk stars

Abstract

We present sodium abundances for a sample of nearby stars. All results have been derived from NLTE statistical equilibrium calculations. The influence of collisional interactions with electrons and hydrogen atoms is evaluated by comparison of the solar spectrum with very precise fits to the Na I line cores. The NLTE effects are more pronounced in metal-poor stars since the statistical equilibrium is dominated by collisions of which at least the electronic component is substantially reduced. The resulting influence on the determination of sodium abundances is in a direction opposite to that found previously for Mg and Al. The NLTE corrections are about -0.1 in thick-disk stars with [Fe/H] about -0.6. Our [Na/Fe] abundance ratios are about solar for thick- and thin-disk stars. The increase in [Na/Fe] as a function of [Fe/H] for metal-rich stars found by Edvardsson et al. (1993) is confirmed. Our results suggest that sodium yields increase with the metallicity, and quite large amounts of sodium may be produced by AGB stars. We find that [Na/Fe]ratios, together with either [Mg/Fe] ratio, kinematic data or stellar evolutionary ages, make possible the individual discrimination between thin- and thick-disk membership.

arXiv comment11pages, 11 figures. A&A accepted

References in corpus (18)

• Local stellar kinematics from Hipparcos data
• Galactic Chemical Evolution: Hydrogen Through Zinc
• The Chemical Compositions of Galactic Disk F and G Dwarfs
• The O-Na and Mg-Al Anticorrelations in Turn-Off and early Subgiants in Globular Clusters
• Abundances and Kinematics of Field Halo and Disk Stars I: Observational Data and Abundance Analysis
• The Galactic Thick Disk Stellar Abundances
• Abundances for metal-poor stars with accurate parallaxes I. Basic data
• Nucleosynthesis in Type Ia Supernovae
• Chemical composition of 90 F and G disk dwarfs
• The Y^2 Stellar Evolutionary Tracks
• Abundances in metal-rich stars - Detailed abundance analysis of 47 G and K dwarf stars with [Me/H] $>$ 0.10 dex
• Abundances and Kinematics of Field Stars II: Kinematics and Abundance Relationships
• Kinetic equilibrium of iron in the atmospheres of cool stars III. The ionization equilibrium of selected reference stars
• Mg, Ba and Eu abundances in thick disk and halo stars
• HIPPARCOS age-metallicity relation of the solar neighbourhood disc stars
• Nucleosynthesis of s-elements in zero-metal AGB stars
• Evolution and Nucleosynthesis of Metal-Free Massive Stars
• Chemical Evolution of Odd Elements in an Inhomogeneous Early Galaxy

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