来自CHARA干涉测量的基准星的基本恒星参数。I.贫金属星
Fundamental stellar parameters of benchmark stars from CHARA interferometry. I. Metal-poor stars
摘要：
基准恒星是至关重要的验证标准，为当前以及未来的银河系大型恒星调查。然而，目前合适的贫金属基准的数量有限。我们的目标是构建一套新的金属贫基准，可靠的干涉有效温度（$T_\text{eff}$）的测定和均匀分析的基础上所需的精度$1\%$在$T_\text{eff}$。我们观测到10颗晚型贫金属矮星和巨星：HD2665、HD 6755、HD 6833、HD 103095、HD 122563、HD 127243、HD 140283、HD 175305、HD221170和HD224930。十颗恒星中只有三颗（HD 103095，HD 122563和HD 140283）以前被用作基准。对于观测，我们在CHARA阵列上使用了高角分辨率的光学干涉仪PAVO。我们使用3D临边暗化模型对角直径进行建模，并直接从Stefan-Boltzmann关系确定$T_\text{eff}$，并使用迭代程序对测热校正表进行插值。表面重力（$\log(g)$）是通过与达特茅斯恒星演化模型轨道的比较来估计的。我们收集了光谱观测的SDUDIE和FIES摄谱仪和估计金属丰度（$\mathrm{[Fe/H]}$）从一维非LTE丰度分析的中性和单离子化铁的未混合线。我们推断其中五颗恒星（HD 103095、HD 122563、HD 127243、HD 140283和HD 224930）的$T_\text{eff}$优于$1\%$。其他5颗恒星的$T_\text{eff}$在$2-3\%$之间是可靠的，这些恒星的$T_\text{eff}$的较高不确定度主要是由于它们的热通量具有较大的不确定度。我们还确定了$\log(g)$和$\mathrm{[Fe/H]}$，中值不确定度分别为$0.03\,\mathrm{dex}$和$0.09\,\mathrm{dex}$。因此，这十颗恒星可以作为一套新的、可靠的贫金属基准。
英文摘要：
Benchmark stars are crucial as validating standards for current as well as future large stellar surveys of the Milky Way. However, the number of suitable metal-poor benchmarks is currently limited. We aim to construct a new set of metal-poor benchmarks, based on reliable interferometric effective temperature ($T_\text{eff}$) determinations and a homogeneous analysis with a desired precision of $1\%$ in $T_\text{eff}$. We observed ten late-type metal-poor dwarf and giants: HD2665, HD6755, HD6833, HD103095, HD122563, HD127243, HD140283, HD175305, HD221170, and HD224930. Only three of the ten stars (HD103095, HD122563, and HD140283) have previously been used as benchmarks. For the observations, we used the high angular resolution optical interferometric instrument PAVO at the CHARA array. We modelled angular diameters using 3D limb darkening models and determined $T_\text{eff}$ directly from the Stefan-Boltzmann relation, with an iterative procedure to interpolate over tables of bolometric corrections. Surface gravities ($\log(g)$) were estimated from comparisons to Dartmouth stellar evolution model tracks. We collected spectroscopic observations from the ELODIE and FIES spectrographs and estimated metallicities ($\mathrm{[Fe/H]}$) from a 1D non-LTE abundance analysis of unblended lines of neutral and singly ionized iron. We inferred $T_\text{eff}$ to better than $1\%$ for five of the stars (HD103095, HD122563, HD127243, HD140283, and HD224930). The $T_\text{eff}$ of the other five stars are reliable to between $2-3\%$; the higher uncertainty on the $T_\text{eff}$ for those stars is mainly due to their having a larger uncertainty in the bolometric fluxes. We also determined $\log(g)$ and $\mathrm{[Fe/H]}$ with median uncertainties of $0.03\,\mathrm{dex}$ and $0.09\,\mathrm{dex}$, respectively. These ten stars can, therefore, be adopted as a new, reliable set of metal-poor benchmarks.
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