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Sodium abundances in nearby disk stars
Shi, JR; Gehren, T; Zhao, G
AbstractWe 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] similar to -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 a]. (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.
KeywordLine : Formation Line : Profiles Stars : Abundances Stars : Late-type Galaxy : Evolution
Indexed BySCI
WOS IDWOS:000223621400034
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Cited Times:39[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Affiliation1.Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China
2.Univ Munich, Inst Astron & Astrophys, D-81679 Munich, Germany
Recommended Citation
GB/T 7714
Shi, JR,Gehren, T,Zhao, G. Sodium abundances in nearby disk stars[J]. ASTRONOMY & ASTROPHYSICS,2004,423(2):683-691.
APA Shi, JR,Gehren, T,&Zhao, G.(2004).Sodium abundances in nearby disk stars.ASTRONOMY & ASTROPHYSICS,423(2),683-691.
MLA Shi, JR,et al."Sodium abundances in nearby disk stars".ASTRONOMY & ASTROPHYSICS 423.2(2004):683-691.
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