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arXiv 2202.09185astro-ph.SRastro-ph.GAastro-ph.IM
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根据LAMOST DR7的光谱特征识别红团簇恒星的质量和年龄

Identification, mass and age of primary red clump stars from spectral features derived with the LAMOST DR7

Xu-Jiang He, A-Li Luo, Yu-Qin Chen

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14 pages, 17 figures, accepted by MNRAS
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摘要：

虽然红团（RC）星由于其光度和颜色的稳定性而易于识别，但在HR图上的同一位置上，大约20-50%的红巨星分支（RGB）星实际上是红巨星。本文从LAMOST DR 7上鉴定了184318颗主RC（PRC）星的210,504个光谱样本，其纯度高于90%。采用XGBoost集成学习算法，通过LAMOST光谱（R~1800，SNR>10）成功区分了RC星和RGB星，并去除了次RC星。SHapley加法解释（SHAP）值用于解释XGBoost模型选择的顶级功能。特征围绕Fe 5270、MgH & MgIb、Fe 4957、Fe 4207、Cr 5208和CN，可以成功区分RGB和RC星。XGBoost也被用来估计PRC恒星的年龄和质量，通过用开普勒标记的星震参数训练它们的光谱。质量和年龄的不确定性分别为13%和31%。通过对特征归因模型的验证，发现XGBoost得到的年龄敏感因素与文献结果一致。PRC星的距离是由Gaia EDR 3标定的$K_{S}$绝对星等推算的，其不确定度约为6%，表明PRC星主要位于银盘上。我们还测试了XGBoost与R $\sim$ 250，这是中国空间站望远镜（CSST）的分辨率正在建设中，它仍然能够找到敏感的功能，以区分RC和RGB。

英文摘要：

Although red clump (RC) stars are easy to identify due to their stability of luminosity and color, about 20-50% are actually red giant branch (RGB) stars in the same location on the HR diagram. In this paper, a sample of 210,504 spectra for 184 318 primary RC (PRC) stars from the LAMOST DR7 is identified, which has a purity of higher than 90 percent. The RC and the RGB stars are successfully distinguished through LAMOST spectra(R~1800 and SNR>10) by adopting the XGBoost ensemble learning algorithm, and the secondary RC stars are also removed. The SHapley Additive exPlanations (SHAP) value is used to explain the top features that the XGBoost model selected. The features are around Fe5270, MgH & MgIb, Fe4957, Fe4207, Cr5208, and CN, which can successfully distinguish RGB and RC stars. The XGBoost is also used to estimate the ages and masses of PRC stars by training their spectra with Kepler labeled asteroseismic parameters. The uncertainties of mass and age are 13 and 31 percent, respectively. Verifying the feature attribution model, we find the age-sensitive elements XGBoost gets are consistent with the literature. Distances of the PRC stars are derived by $K_{S}$ absolute magnitude calibrated by Gaia EDR3, which has an uncertainty of about 6 percent and shows the stars mainly locate at the Galactic disk. We also test the XGBoost with R$\sim$250, which is the resolution of the Chinese Space Station Telescope(CSST) under construction, it is still capable of finding sensitive features to distinguish RC and RGB.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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