论文标题
低分辨率光谱的氮与铁的丰度比估计
Estimation of Nitrogen-to-Iron Abundance Ratios From Low-Resolution Spectra
论文作者
论文摘要
我们提出了一种方法，可以从分子CN波段（[$ r \ sim $ 2000）在Sloan Digital Sky Survey（SDS）和大型Sky Sky Area Multi-Sky Multi-Optim-Optim-Oppim Multi-Oppimpoct Fiber eppectroscopic telescope（lameScope（lam）中获得的分子CN波段特征（$ r \ sim $ 2000）在低分辨率（$ r \ sim $ 2000）中观察到的铁（[n/fe]）的方法。进行了各种测试以检查我们技术的系统和随机误差，以及恒星光谱对确定的[N/FE]的信噪比（S/N）比率的影响。我们发现，S/n比的不确定性小于0.3 dex，大于10的范围$ t_ {eff} $ = [4000，6000] k，log g = [0.0，3.5]，[fe/h]，[fe/h] = [-3.0，0.0]，[-3.0]，[c/fe]，[c/fe]，[c/fe] = [c/fe]我们感兴趣的参数空间以鉴定银河系中的N增强恒星。逐行的星星与恒星样品具有[N/Fe]估计值的样本，可从Apache Point观测值银河进化实验（Apogee）可用，这也表明我们所测量的[N/FE]在删除其系统错误后的不确定性水平相似。基于这些结果，我们得出的结论是，我们的方法能够从低分辨率光谱数据中繁殖[N/Fe]，其不确定性足够小，可以发现富含N的恒星，这些恒星可能源自破坏的银河球状簇。
We present a method to determine nitrogen abundance ratios with respect to iron ([N/Fe]) from molecular CN-band features observed in low-resolution ($R \sim$ 2000) stellar spectra obtained by the Sloan Digital Sky Survey (SDSS) and the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). Various tests are carried out to check the systematic and random errors of our technique, and the impact of signal-to-noise (S/N) ratios of stellar spectra on the determined [N/Fe]. We find that the uncertainty of our derived [N/Fe] is less than 0.3 dex for S/N ratios larger than 10 in the ranges $T_{eff}$ = [4000, 6000] K, log g = [0.0, 3.5], [Fe/H] = [--3.0, 0.0], [C/Fe] = [--1.0, +4.5], and [N/Fe] = [--1.0, +4.5], the parameter space that we are interested in to identify N-enhanced stars in the Galactic halo. A star-by-star comparison with a sample of stars with [N/Fe] estimates available from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) also suggests a similar level of uncertainty in our measured [N/Fe], after removing its systematic error. Based on these results, we conclude that our method is able to reproduce [N/Fe] from low-resolution spectroscopic data, with an uncertainty sufficiently small to discover N-rich stars that presumably originated from disrupted Galactic globular clusters.
