Fundamental parameters are determined for three bright, nearby K-giants, {\beta} Gem (K0 III), {\mu} Leo (K2 III), and {\alpha} Tau (K5 III). It is notable that around all three stars the giant planets have been found. Our results are compared with published high-precision data for benchmark stars included in the Gaia project. Very good agreement was obtained for all three giants with these data for the basic parameters Teff, logg, and M. Special attention was devoted to analysis of the Fe I lines which are the basis of a simultaneous determination of the metallicity index [Fe/H] and microturbulent parameter Vt. The equivalent widths W of the Fe I lines are automatically measured from published spectra for the benchmark stars. An analysis of Fe I lines from the list of "golden lines" selected in a study of benchmark stars led to the conclusion that the excitation potential El of the low level of the lines plays an substantial role in determining [Fe/H] and Vt. It is shown that in the case of the early K-giants {\beta} Gem and {\mu} Leo for lines in the range of W from 100 to 300 mA there is a dependence of the [Fe/H] and Vt values on El. It is shown that a correct accounting for it leads an ambiguity in the determination of [Fe/H] and Vt for {\beta} Gem and {\mu} Leo. In the case of the coolest K-giant {\alpha} Tau (Aldebaran) with a temperature Teff = 3920K, this effect seems to be less pronounced. Recommendations are given for the Fe I lines selection for [Fe/H] and Vt determination. It is sonfirmed for the example of the three stars studied here that the non-LTE effects in the Fe I lines for the K-giants with normal metallicity are very minor, so they cannot be the reason of the revealed ambiguity in [Fe/H] and Vt values. The low ratios of the carbon 12C/13C and oxygen 16O/17O isotopes confirm that all three giants passed the phase of deep convective mixing.

中文翻译：

---

附近有行星的三颗 K 巨星：准确确定基本参数，包括基于 Fe I 谱线的金属度分析

确定了三个明亮的附近 K 巨星的基本参数，{\beta} Gem (K0 III)、{\mu} Leo (K2 III) 和 {\alpha} Tau (K5 III)。值得注意的是，在所有三颗恒星周围都发现了巨行星。我们的结果与盖亚项目中包含的基准恒星的已发布高精度数据进行了比较。所有三个巨星的基本参数 Teff、logg 和 M 的这些数据都获得了非常好的一致性。 特别注意分析 Fe I 谱线，这是同时确定金属丰度指数 [Fe/H ] 和微湍流参数 Vt。Fe I 线的等效宽度 W 是根据已发布的基准星光谱自动测量的。从“金线”列表中分析Fe I线 在基准星研究中选择得出的结论是，谱线低能级的激发势 El 在确定 [Fe/H] 和 Vt 方面起着重要作用。 结果表明，在早期 K 巨星的情况下{\beta} Gem 和 {\mu} Leo 对于 W 范围从 100 到 300 mA 的线，[Fe/H] 和 Vt 值依赖于 El。结果表明，对它的正确解释导致 {\beta} Gem 和 {\mu} Leo 的 [Fe/H] 和 Vt 的确定存在歧义。在温度 Teff = 3920K 的最冷 K 巨星 {\alpha} Tau (Aldebaran) 的情况下，这种影响似乎不那么明显。给出了用于 [Fe/H] 和 Vt 测定的 Fe I 谱线选择的建议。以这里研究的三颗星为例，可以肯定的是，对于金属丰度正常的 K 巨星，Fe I 谱线中的非 LTE 效应非常小，因此它们不能成为 [Fe/H ] 和 Vt 值。碳 12C/13C 和氧 16O/17O 同位素的低比率证实所有三个巨星都通过了深度对流混合阶段。