论文标题
光谱测定恒星参数和hyades/field g-k矮人的氧气丰度
Spectroscopic Determination of Stellar Parameters and Oxygen Abundances for Hyades/Field G-K Dwarfs
论文作者
论文摘要
偶尔有人提出，源自Fe I和Fe II线的K矮人的Fe丰度表现出很大的差异和氧气丰度，从高兴奋的o I 7771-5三胞胎线上明显地高估了（问题变得更加严重，降低了Teff），但是尚未得到广泛证实，这尚未得到广泛证实。为了澄清这个问题，我们通过假设经典的Fe I/Fe I/Fe II/Fe II离子化平衡来确定148 G-K矮人（Hyades Cluster Star and Field Stars）的大气参数，并确定其氧气丰度，并通过将非LTE Spectrum Spectrum Spectrum Spectrum Spectrum Spectrum Spectrum拟合分析应用于O I 777777777777771-5系。事实证明，所产生的参数与其他方法确定的参数没有任何明显的不一致（例如，从hyades矮人的hyades矮人解决方案中的TEFF和log g的平均差异主要<〜100K和<〜0.1dex）。同样，hyades恒星的氧丰度在没有表现出任何系统的TEFF依赖性的情况下围绕[O/H]〜+0.2DEX（与该簇的金属性一致）。因此，我们得出的结论是，可以通过传统方式将参数评估为足够的精度（基于Fe I/Fe II/Fe II的Saha-Boltzmann方程），并且可以从O I 7771-5三倍的Teff> 〜450000涉及的k dwarfs的o 7771-5三倍体中可靠地确定氧气丰度。我们怀疑先前报道的TEFF依赖性差异可能主要是由于高估弱线强度和/或TEFF量表的高估。
It has been occasionally suggested that Fe abundances of K dwarfs derived from Fe I and Fe II lines show considerable discrepancies and oxygen abundances determined from high-excitation O I 7771-5 triplet lines are appreciably overestimated (the problem becoming more serious towards lower Teff), which however has not yet been widely confirmed. With an aim to clarify this issue, we spectroscopically determined the atmospheric parameters of 148 G-K dwarfs (Hyades cluster stars and field stars) by assuming the classical Fe I/Fe II ionization equilibrium as usual, and determined their oxygen abundances by applying the non-LTE spectrum fitting analysis to O I 7771-5 lines. It turned out that the resulting parameters did not show any significant inconsistency with those determined by other methods (for example, the mean differences in Teff and log g from the well-determined solutions of Hyades dwarfs are mostly <~100K and <~0.1dex). Likewise, the oxygen abundances of Hyades stars are around [O/H]~+0.2dex (consistent with the metallicity of this cluster) without exhibiting any systematic Teff-dependence. Accordingly, we conclude that parameters can be spectroscopically evaluated to a sufficient precision in the conventional manner (based on the Saha-Boltzmann equation for Fe I/Fe II) and oxygen abundances can be reliably determined from the O I 7771-5 triplet for K dwarfs as far as stars of Teff>~4500K are concerned. We suspect that previously reported strongly Teff-dependent discrepancies may have stemmed mainly from overestimation of weak-line strengths and/or improper Teff scale.
