Fundamental stellar parameters of benchmark stars from CHARA interferometry: I. Metal-poor stars
Fundamental stellar parameters of benchmark stars from CHARA interferometry: I. Metal-poor stars
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CHARA 干涉测量基准恒星的基本恒星参数：I. 贫金属恒星
DOI：
10.1051/0004-6361/202037590
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发表时间：
2020
影响因子：
6.5
通讯作者：
Jofré, P.
中科院分区：
文献类型：
--
作者：
Karovicova, I.;White, T. R.;Nordlander, T.;Casagrande, L.;Ireland, M.;Huber, D.;Jofré, P.
作为验证银河系当前和未来大型恒星观测的标准，ConextBenchmark恒星至关重要。然而，目前合适的贫金属基准星的数量是有限的，因为该方案很难确定可靠的有效温度。目的基于可靠的干涉有效温度测定和均匀分析，我们旨在构建一套新的贫金属基准星。目标是达到1%的精度，这对于足够准确地确定调查来源的全套基本参数和丰度是至关重要的。方法我们观察了10颗晚型贫金属矮星和巨星：HD2665、HD6755、HD6833、HD 103095、HD 122563、HD 127243、HD 140283、HD 175305、HD 221170和HD 224930。其中只有三个(高清103095、高清122563和高清140283)之前被用作基准明星。为了进行观测，我们在查拉阵列上使用了高角分辨率的光学干涉仪器PAVO。我们使用3D边缘变暗模型来模拟角直径，并直接从Stefan-Boltzmann关系中确定有效温度，并使用迭代程序在测热校正表上进行内插。表面引力(log(G))是通过与达特茅斯恒星演化模型轨迹的比较来估计的。我们收集了来自Elodie和FIES光谱仪的光谱观测，并通过一维非局域热力学平衡丰度分析估计了中性和单离化铁的未混合谱线的金属度([Fe/H])。结果我们推断，其中5颗恒星(HD 103095、HD 122563、HD 127243、HD 140283和HD 224930)的效果好于1%。其他5颗恒星的有效温度在2%-3%之间是可靠的；这些恒星的有效温度的不确定度较高，主要是因为它们在测辐射热通量上有较大的不确定性。我们还测定了LOG(G)和[Fe/H]，中位不确定度分别为0.03Dex和0.09Dex。结论本研究为10颗贫金属星提供了可靠和均匀的基本恒星参数，可作为一套新的基准。这些参数是基于我们将干涉观测、三维边缘变暗建模和光谱观测相结合的一贯方法。本系列的下一篇论文将把这种方法扩展到金属丰富地区的矮人和巨人。
ContextBenchmark 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 benchmark stars is currently limited, owing to the difficulty in determining reliable effective temperatures (Teff) in this regime.AimsWe aim to construct a new set of metal-poor benchmark stars based on reliable interferometric effective temperature determinations and a homogeneous analysis. The aim is to reach a precision of 1% inTeff, as is crucial for sufficiently accurate determinations of the full set of fundamental parameters and abundances for the survey sources.MethodsWe observed ten late-type metal-poor dwarfs and giants: HD 2665, HD 6755, HD 6833, HD 103095, HD 122563, HD 127243, HD 140283, HD 175305, HD 221170, and HD 224930. Only three of them (HD 103095, HD 122563, and HD 140283) have previously been used as benchmark stars. 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 effective temperatures 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 ([Fe/H]) from a 1D non-local thermodynamic equilibrium (NLTE) abundance analysis of unblended lines of neutral and singly ionised iron.ResultsWe inferredTeffto better than 1% for five of the stars (HD 103095, HD 122563, HD 127243, HD 140283, and HD 224930). The effective temperatures of the other five stars are reliable to between 2 and 3%; the higher uncertainty on theTefffor those stars is mainly due to their having a larger uncertainty in the bolometric fluxes. We also determined log(g) and [Fe/H] with median uncertainties of 0.03 dex and 0.09 dex, respectively.ConclusionsThis study presents reliable and homogeneous fundamental stellar parameters for ten metal-poor stars that can be adopted as a new set of benchmarks. The parameters are based on our consistent approach of combining interferometric observations, 3D limb-darkening-modelling and spectroscopic observations. The next paper in this series will extend this approach to dwarfs and giants in the metal-rich regime.