STELLAR CHEMICAL ABUNDANCES: IN PURSUIT OF THE HIGHEST ACHIEVABLE PRECISION
STELLAR CHEMICAL ABUNDANCES: IN PURSUIT OF THE HIGHEST ACHIEVABLE PRECISION
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一流的化学丰度：追求可达到的最高精度
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
M. Asplund
中科院分区：
文献类型：
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作者：
M. Bedell;J. Meléndez;J. Bean;I. Ramírez;P. Leite;M. Asplund
恒星光球丰度可达到的精度水平是研究系外行星宿主恒星特征、星团化学历史以及银河系和其他星系演化的主要限制因素。虽然可以通过对光谱相似的恒星进行差分分析来最小化模型引起的误差，但该技术可实现的最大精度一直存在争议。作为测试，我们从使用各种仪器和条件获取的高质量小行星反射太阳光谱中得出了 19 种元素的差异丰度。我们将太阳光谱视为来自未知恒星，并使用由此产生的差异丰度（预计为零）作为我们测量误差的诊断。我们的结果表明，目标光谱和参考光谱的相对分辨率是一个主要考虑因素，使用不同的仪器获得两个光谱会导致高达 0.04 dex 的误差。在不同时期使用同一仪器对两个光谱的影响要小得多（∼0.007 dex）。用于获得太阳标准的小行星的影响也可以忽略不计（∼0.006 dex）。假设恒星模型大气的系统误差已经最小化，就像太阳双胞胎的情况一样，我们确认，在观测、数据缩减和丰度分析中，只要小心谨慎，就可以以低于 0.01 dex 的精度获得差异化学丰度。
The achievable level of precision on photospheric abundances of stars is a major limiting factor on investigations of exoplanet host star characteristics, the chemical histories of star clusters, and the evolution of the Milky Way and other galaxies. While model-induced errors can be minimized through the differential analysis of spectrally similar stars, the maximum achievable precision of this technique has been debated. As a test, we derive differential abundances of 19 elements from high-quality asteroid-reflected solar spectra taken using a variety of instruments and conditions. We treat the solar spectra as being from unknown stars and use the resulting differential abundances, which are expected to be zero, as a diagnostic of the error in our measurements. Our results indicate that the relative resolution of the target and reference spectra is a major consideration, with use of different instruments to obtain the two spectra leading to errors up to 0.04 dex. Use of the same instrument at different epochs for the two spectra has a much smaller effect (∼0.007 dex). The asteroid used to obtain the solar standard also has a negligible effect (∼0.006 dex). Assuming that systematic errors from the stellar model atmospheres have been minimized, as in the case of solar twins, we confirm that differential chemical abundances can be obtained at sub-0.01 dex precision with due care in the observations, data reduction, and abundance analysis.