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arXiv 2201.05837astro-ph.SRastro-ph.GAastro-ph.IM
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冷巨星的$H$波段温度和金属丰度指标：贝叶斯框架下的经验关系

$H$-band Temperature and Metallicity Indicators for Cool Giants: Empirical Relations in Bayesian Framework

Supriyo Ghosh, J. P. Ninan, D. K. Ojha

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15 pages, 16 figures, 5 tables. Accepted for publication in MNRAS
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摘要：

我们探索了近红外$H$波段大气窗口，旨在为利用低分辨率光谱推导冷巨星（$T_{eff}$ $<$ 5000 K）的恒星参数，例如有效温度（$T_{eff}$）和金属丰度（[ $Fe/H$ ]）提供定量诊断工具。我们从X-shooter光谱库中获得了177颗冷巨星，覆盖了比早期作品更宽的金属丰度范围（$-$ 2.35 dex $<$ [ $Fe/H$ ] $<$ 0.5 dex）。将光谱分辨率降低到R $\sim$ 1200，估算了几个重要光谱特征的等效宽度，并研究了光谱特征随恒星参数的变化规律。在贝叶斯框架下建立了推导$T_{eff}$和[ $Fe/H$ ]的经验关系。我们发现，$^{12}$ CO在1.56 $μ$ m和1.62 $μ$ m，以及$^{12}$ CO+MgI在1.71 $μ$ m是最好的三个$T_{eff}$指标，具有典型的准确度分别为153 K，123 K和107 K。三次贝叶斯模型提供了最佳金属丰度估计值，对于1.62 $μ$ m处的FeH、1.64 $μ$ m处的$^{12}$ CO和1.66 $μ$ m处的Fe I，其典型精度分别为0.22 dex、0.28 dex和0.24 dex。我们还显示了详细的定量金属丰度依赖性的$T_{eff}-$ EWs相关性定义三个金属丰度组，超日的（[ $Fe/H$ ] $>$ 0.0 dex），太阳的（$-$ 0.3 dex $<$ [ $Fe/H$ ] $<$ 0.3 dex），太阳下（[ $Fe/H$ ] $<$ $-$ 0.3 dex），来自分层贝叶斯建模。太阳和日下关系之间的差异在统计上是显著的，但这种差异在太阳和太阳集团之间并不明显。

英文摘要：

We explored here the near-infrared $H$-band atmospheric window aiming to provide quantitative diagnostic tools for deriving stellar parameters, for instance, effective temperature ($T_{eff}$) and metallicity ([$Fe/H$]), of cool giants ($T_{eff}$ $<$ 5000 K) using low-resolution spectra. We obtained 177 cool giants from the X-shooter spectral library covering a wider metallicity range ($-$2.35 dex $<$ [$Fe/H$] $<$ 0.5 dex) than in earlier works. Degrading the spectral resolution to R$\sim$ 1200, we estimated equivalent widths of several important spectral features, and the behavior of spectral features with stellar parameters are studied. Also, the empirical relations for deriving $T_{eff}$ and [$Fe/H$] are established in the Bayesian framework. We found that $^{12}$CO at 1.56 $μ$m and 1.62 $μ$m, and $^{12}$CO+MgI at 1.71 $μ$m are the best three $T_{eff}$ indicators with a typical accuracy of 153 K, 123 K and 107 K, respectively. The cubic Bayesian model provides the best metallicity estimator with a typical accuracy of 0.22 dex, 0.28 dex, and 0.24 dex for FeH at 1.62 $μ$m, $^{12}$CO at 1.64 $μ$m, and Fe I at 1.66 $μ$m, respectively. We also showed a detailed quantitative metallicity dependence of $T_{eff}-$EWs correlations defining three metallicity groups, supersolar ([$Fe/H$] $>$ 0.0 dex), solar ($-$0.3 dex $<$ [$Fe/H$] $<$ 0.3 dex), and subsolar ([$Fe/H$] $<$ $-$0.3 dex), from Hierarchical Bayesian modelling. The difference between the solar and subsolar relationship is statistically significant, but such difference is not evident between the solar and supersolar groups.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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