关于MILES恒星库的光谱分辨率
On the spectral resolution of the MILES stellar library
摘要：
经验恒星库被广泛用于提取星系中的恒星运动学和建立恒星星族模型。这些图书馆的光谱分辨率的准确知识是至关重要的，以避免传播误差和不确定的估计星系的内在恒星速度色散。在这篇研究报告中，我们重新评估了MILES恒星库和基于它的恒星星族模型的光谱分辨率。我们通过比较MILES恒星光谱与三组不同的高分辨率模板进行测试，一组是完全理论的-MARCS库-两个是经验的，即Indo-U.S.和ESDIE v3.1库。理论模板具有良好定义的非常高的（R=20000）分辨率。因此，这个理论值的误差并不影响我们的结论。我们的方法的基础上的MARCS库是至关重要的约束值的决议也为其他两个经验模板。我们发现，以前的MILES分辨率略有高估。我们得到了一个新的光谱分辨率为2.54 A的FWHM，而不是标称的2.3 A。这种差异的原因是由于高估了以前用于估计MILES分辨率的Indo-U.S.库的分辨率。对于印-美，我们得到了1.35A的新的半高宽值.最重要的是，从MARCS和MARDIE库得到的结果非常一致。这些结果对于MILES谱库的用户和进一步发展旨在获得星系中精确恒星运动学的恒星星族模型具有重要意义。
英文摘要：
Empirical stellar libraries are extensively used to extract stellar kinematics in galaxies and to build stellar population models. An accurate knowledge of the spectral resolution of these libraries is critical to avoid propagation errors and uncertain estimates of the intrinsic stellar velocity dispersion of galaxies. In this research note we re-assess the spectral resolution of the MILES stellar library and of the stellar population models based on it. This exercise was performed, because of a recent controversy over the exact MILES resolution. We perform our test through the comparison of MILES stellar spectra with three different sets of higher-resolution templates, one fully theoretical - the MARCS library - and two empirical ones, namely the Indo-U.S. and ELODIE v3.1 libraries. The theoretical template has a well-defined very high (R=20000) resolution. Hence errors on this theoretical value do not affect our conclusions. Our approach based on the MARCS library was crucial to constrain the values of the resolution also for the other two empirical templates. We find that the MILES resolution has previously been slightly overestimated. We derive a new spectral resolution of 2.54 A FWHM, instead of the nominal 2.3 A. The reason for this difference is due to an overestimation of the resolution for the Indo-U.S. library that was previously used for estimates of the MILES resolution. For the Indo-U.S. we obtain a new value of 1.35 A FWHM. Most importantly, the results derived from the MARCS and ELODIE libraries are in very good agreement. These results are important for users of the MILES spectra library and for further development of stellar population models aimed to obtain accurate stellar kinematics in galaxies.
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