منابع مشابه
Sodium abundances in nearby disk stars ⋆
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 equilibri...
متن کاملOxygen Abundances in Metal-poor Stars
We present oxygen abundances derived from both the permitted and forbidden oxygen lines for 55 subgiants and giants with [Fe/H] values between −2.7 and solar with the goal of understanding the discrepancy in the derived abundances. A first attempt, using Teff values from photometric calibrations and surface gravities from luminosities, obtained agreement between the indicators for turn-off star...
متن کاملElemental abundances of carbon, nitrogen, and oxygen in carbon stars
The elemental abundances of carbon, nitrogen, and oxygen in three carbon stars (TX Psc, V Aql, and BL Ori) are determined from high-resolution infrared spectra in a selfconsistent manner, with the dependence of the atmospheric structure on the chemical composition fully taken into account. For this purpose, we have constructed a grid of line-blanketed model atmospheres using a revised Band Mode...
متن کاملOn the determination of oxygen abundances in chromospherically active stars
We discuss oxygen abundances derived from [O ] λ6300 and the O triplet in stars spanning a wide range in chromospheric activity level, and show that these two indicators yield increasingly discrepant results with higher chromospheric/coronal activity measures. While the forbidden and permitted lines give fairly consistent results for solar-type disk dwarfs, spuriously high O triplet abunda...
متن کاملAbundances in stars with exoplanets
Extensive spectroscopic studies of stars with and without planets have concluded that stars hosting planets are significantly more metal-rich than those without planets. More subtle trends of different chemical elements begin to appear as the number of detected extrasolar planetary systems continues to grow. I review our current knowledge concerning the observed abundance trends of various chem...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2006
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361:20066619