Fundamental M-dwarf parameters from high-resolution spectra using PHOENIX ACES models: I. Parameter accuracy and benchmark stars
Fundamental M-dwarf parameters from high-resolution spectra using PHOENIX ACES models: I. Parameter accuracy and benchmark stars
复制标题
使用 PHOENIX ACES 模型从高分辨率光谱中获取基本 M 矮星参数：I 参数精度和基准恒星
DOI：
10.1051/0004-6361/201322261
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Reiners
中科院分区：
文献类型：
--
作者：
Passegger;Wende-von Berg;Reiners
M矮星是宇宙中数量最多的恒星;它们的质量跨度很大，是正在进行和计划中的系外行星调查的重点。为了研究和理解它们的物理性质，需要详细的光谱信息和精确的恒星模型。我们使用一个新的合成大气模型生成和比较模型光谱观测。为了测试模型的准确性，我们比较了四个基准星的大气参数，独立的信息，从干涉半径测量。我们使用基于χ2的方法来确定高分辨率光谱观测的参数。我们的合成光谱是基于新的PHOENIX网格，使用ACES描述的状态方程。这是一种特别适用于低温大气的模型。我们确定了合适的光谱示踪剂的大气参数和确定的不确定性inTeff，logg，和[Fe/H]参数之间的退化和模型大气的缺点。我们发现的固有不确定度为σTeff= 35 K，σlogg= 0.14，σ[Fe/H]= 0.11。新的模型谱与我们的观测数据实现了可靠的匹配;我们对Tef和log的结果与文献值在1σ内一致。然而，从早期的光度和光谱校准报告的金属丰度在某些情况下不同意我们的结果超过3σ。一个可能的解释是早期金属丰度测定中的系统性错误，这些错误是基于对冷大气的不充分描述。然而，在这一点上，我们不能确定这种差异的原因，但我们的分析表明，M矮星参数估计的准确性存在很大的不确定性。
M-dwarf stars are the most numerous stars in the Universe; they span a wide range in mass and are in the focus of ongoing and planned exoplanet surveys. To investigate and understand their physical nature, detailed spectral information and accurate stellar models are needed. We use a new synthetic atmosphere model generation and compare model spectra to observations. To test the model accuracy, we compared the models to four benchmark stars with atmospheric parameters for which independent information from interferometric radius measurements is available. We usedχ2-based methods to determine parameters from high-resolution spectroscopic observations. Our synthetic spectra are based on the new PHOENIX grid that uses the ACES description for the equation of state. This is a model generation expected to be especially suitable for the low-temperature atmospheres. We identified suitable spectral tracers of atmospheric parameters and determined the uncertainties inTeff, logg, and [Fe/H] resulting from degeneracies between parameters and from shortcomings of the model atmospheres. The inherent uncertainties we find areσTeff= 35 K,σlogg= 0.14, andσ[Fe/H]= 0.11. The new model spectra achieve a reliable match to our observed data; our results forTeffand loggare consistent with literature values to within 1σ. However, metallicities reported from earlier photometric and spectroscopic calibrations in some cases disagree with our results by more than 3σ. A possible explanation are systematic errors in earlier metallicity determinations that were based on insufficient descriptions of the cool atmospheres. At this point, however, we cannot definitely identify the reason for this discrepancy, but our analysis indicates that there is a large uncertainty in the accuracy of M-dwarf parameter estimates.