Deriving precise parameters for cool solar-type stars Optimizing the iron line list ?;??;???
Deriving precise parameters for cool solar-type stars Optimizing the iron line list ?;??;???
复制标题
导出冷太阳型恒星的精确参数优化铁线列表??;??;???
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
G. Israelian
中科院分区：
文献类型：
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作者：
M. Tsantaki;S. Sousa;S. Sousa;V. Adibekyan;N. Santos;A. Mortier;G. Israelian
上下文。温度、表面重力和金属量是描述恒星特征所必需的基本恒星大气参数。有几种方法可以得出这些参数，它们的结果的比较经常显示出相当大的差异，即使在太阳型FGK矮星的有限群体中也是如此。目标。我们想要检查基于铁谱线的标准光谱技术与红外通量法（IRFM）之间的温度差异。我们的目标是改进光谱温度的描述，特别是对于两种方法之间差异较大的较冷恒星，正如以前的工作所提出的那样。方法。我们的光谱分析是基于铁激发和电离平衡，假设LTE中的Kurucz模型大气。丰度分析是使用代码MOOG确定的。我们使用具有高分辨率和高信噪光谱的冷星（HD 21749）优化线路列表，作为参考，以检查弱隔离线路。结果。我们通过重新导出451颗恒星的高分辨率和信号-噪声HARPS光谱来测试新线列表的质量，这些恒星在之前的工作中使用更大的线列表进行了分析。与最新的普通恒星的IRFM温度比较表明，对于温度低于5000 K的恒星，较冷恒星的差异明显更小，分布更均匀。此外，尽管样本很小，平均差的误差很大，但干涉温度与我们的结果之间的比较显示出很好的一致性。我们使用新的谱线表来重新推导一些拥有行星的较冷恒星的参数。最后，我们给出了新温度对[Cri/Crii]和[Tii/Tiii]丰度比的影响。我们表明，温度较低的恒星的这些趋势斜率急剧变小。
Context. Temperature, surface gravity, and metallicitity are basic stellar atmospheric parameters necessary to characterize a star. There are several methods to derive these parameters and a comparison of their results often shows considerable discrepancies, even in the restricted group of solar-type FGK dwarfs. Aims. We want to check the di erences in temperature between the standard spectroscopic technique based on iron lines and the Infrared Flux Method (IRFM). We aim to improve the description of the spectroscopic temperatures especially for the cooler stars where the di erences between the two methods are higher, as presented in previous work. Methods. Our spectroscopic analysis is based on the iron excitation and ionization balance, assuming Kurucz model atmospheres in LTE. The abundance analysis is determined using the code MOOG. We optimize the line list using a cool star (HD 21749) with high resolution and high signal-to-noise spectrum, as a reference in order to check for weak, isolated lines. Results. We test the quality of the new line list by re-deriving stellar parameters for 451 stars with high resolution and signal-tonoise HARPS spectra, that were analyzed in a previous work with a larger line list. The comparison in temperatures between this work and the latest IRFM for the stars in common shows that the di erences for the cooler stars are significantly smaller and more homogeneously distributed than in previous studies for stars with temperatures below 5000 K. Moreover, a comparison is presented between interferometric temperatures with our results that shows good agreement, even though the sample is small and the errors of the mean di erences are large. We use the new line list to re-derive parameters for some of the cooler stars that host planets. Finally, we present the impact of the new temperatures on the [Cri/Crii] and [Tii/Tiii] abundance ratios that previously showed systematic trends with temperature. We show that the slopes of these trends for the cooler stars become drastically smaller.