SEGUE样品中的二元污染：对恒星大气参数的SSPP测定的影响
Binary Contamination in the SEGUE sample: Effects on SSPP Determinations of Stellar Atmospheric Parameters
摘要：
使用数值模拟和网格的合成光谱，我们研究的影响，未解决的二进制的SEGUE目标使用SEGUE恒星参数管道（SSPP）测量的各种恒星大气参数的确定。为了模拟SEGUE样本中可能存在的未检测到的双星，我们使用了主星和次星的各种质量分布，并结合经验确定的轨道参数关系，以确定G-K矮星的比例，如SDSS颜色切割所定义的，这将与次级伴星混合。我们专注于SEGUE中的G-K矮星样本，因为它记录了我们银河系化学富集的历史。为了确定次级对光谱参数的影响，我们使用TurboSpectrum从MARCS模型大气合成了3275至7850 K（~0.1至1.0 \msun）和[Fe/H]=-0.5至-2.5的网格模型光谱。我们分析了“无限”信噪比（S/N）模型和退化版本，中值S/N为50，25和10。通过SSPP运行单个和组合光谱（代表双星），我们确定约10%的S/N>=25的混合G-K矮星对将具有其大气参数测定，特别是温度和金属丰度，明显受到未检测到的次级恒星的影响。为了考虑S/N~10时二元污染带来的额外不确定性，必须将~140 K和~0.17 dex [Fe/H]的不确定性与SSPP已发布的不确定性正交添加。（节录）
英文摘要：
Using numerical modeling and a grid of synthetic spectra, we examine the effects that unresolved binaries have on the determination of various stellar atmospheric parameters for SEGUE targets measured using the SEGUE Stellar Parameter Pipeline (SSPP). To model undetected binaries that may be in the SEGUE sample, we use a variety of mass distributions for the primary and secondary stars in conjunction with empirically determined relationships for orbital parameters to determine the fraction of G-K dwarf stars, as defined by SDSS color cuts, that will be blended with a secondary companion. We focus on the G-K dwarf sample in SEGUE as it records the history of chemical enrichment in our galaxy. To determine the effect of the secondary on the spectroscopic parameters, we synthesize a grid of model spectra from 3275 to 7850 K (~0.1 to 1.0 \msun) and [Fe/H]=-0.5 to -2.5 from MARCS model atmospheres using TurboSpectrum. We analyze both "infinite" signal-to-noise ratio (S/N) models and degraded versions, at median S/N of 50, 25 and 10. By running individual and combined spectra (representing the binaries) through the SSPP, we determine that ~10% of the blended G-K dwarf pairs with S/N>=25 will have their atmospheric parameter determinations, in particular temperature and metallicity, noticeably affected by the presence of an undetected secondary. To account for the additional uncertainty from binary contamination at a S/N~10, uncertainties of ~140 K and ~0.17 dex in [Fe/H] must be added in quadrature to the published uncertainties of the SSPP. (Abridged)
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