在2.3 $μ$ m处CO指数区域的一个新恒星库。新的指数定义和经验拟合函数
A new stellar library in the region of the CO index at 2.3 $μ$m. New index definition and empirical fitting functions
摘要：
内容：对未分辨的恒星星族的分析需要具有真实物理成分和扩展波长覆盖范围的演化合成模型。目的：获得2.3 $μ$ m处的第一CO带头的定量描述，以使恒星星族模型能够在该波长范围内提供改进的预测。方法：我们已经观察到一个新的恒星库，比以前的作品有更好的恒星大气参数空间的覆盖范围。我们已经进行了详细的分析，以前的CO指数定义的光谱分辨率，波长校准，信噪比，和通量校准的鲁棒性。结果如下：我们定义了一个新的线强度指数的第一CO带头在2.3 $μ$ m，D $_{\rm CO}$，更适合于恒星星族的研究比以前的指数定义。我们计算经验拟合函数的CO功能作为恒星参数（T $_{\rm eff}$，$\log g$和[Fe/H]）的函数，显示了详细的定量金属丰度的依赖。
英文摘要：
Context: The analysis of unresolved stellar populations demands evolutionary synthesis models with realistic physical ingredients and extended wavelength coverage. Aims: To obtain a quantitative description of the first CO bandhead at 2.3 $μ$m, to allow stellar population models to provide improved predictions in this wavelength range. Methods: We have observed a new stellar library with a better coverage of the stellar atmospheric parameter space than preceding works. We have performed a detailed analysis of the robustness of previous CO index definitions with spectral resolution, wavelength calibration, signal-to-noise ratio, and flux calibration. Results: We define a new line-strength index for the first CO bandhead at 2.3 $μ$m, D$_{\rm CO}$, better suited for stellar population studies than previous index definitions. We compute empirical fitting functions for the CO feature as a function of the stellar parameters (T$_{\rm eff}$, $\log g$ and [Fe/H]), showing a detailed quantitative metallicity dependence.
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