The Stellar Abundances and Galactic Evolution Survey (SAGES). IV. Surface Gravity Estimation and Giant–Dwarf Separation with the DDO51 Filter

作者：Qiqian Zhang, Zhou Fan, Gang Zhao, Ying Wu, Wei Wang, Kai Xiao, Hongrui Gu, Jie Zheng, Jingkun Zhao, Chun Li, Yuqin Chen, Haibo Yuan, Haining Li, Kefeng Tan, Yihan Song, A-Li Luo, Nan Song, Yujuan Liu, Yaqian Wu · 发表于：The Astrophysical Journal · 年份：2025 · DOI：10.3847/1538-4357/ae060c · 被引用次数：1 · 研究领域：Stellar, planetary, and galactic studies、Astronomy and Astrophysical Research、Galaxies: Formation, Evolution, Phenomena

Abstract Reliable estimation of stellar surface gravity (log g ) for a large sample is crucial for evaluating stellar evolution models and understanding galactic structure; however, it is not easy to accomplish due to the difficulty in gathering a large spectroscopic data set. A photometric sky survey using a specific filter, on the other hand, can play a substantial role in the assessment of log g . The Stellar Abundances and Galactic Evolution Survey (SAGES) utilizes eight filters to provide accurate stellar parameters for ∼10 7 stars, with its DDO51 intermediate-band filter specifically designed for robust log g determination. In this work, the observed SAGES u SC and v SAGES photometry and the synthetic photometry in the g , r , i , and DDO51 bands derived from Gaia XP spectra are employed to investigate the importance of the DDO51 filter in the determination of log g . We applied machine learning-based extinction correction and employed XGBoost models, trained on stellar parameters from Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), to predict log g using photometric data. By comparing the model-predicted log g with LAMOST values, we find that including the DDO51 filter improves the accuracy of log g estimates by 21.0% (from 0.224 to 0.177 dex) overall and by 26.5% (from 0.302 to 0.222 dex) for G- and K-type stars as compared to those obtained without DDO51. The DDO51 filter is also validated to be particularly effective for metal-poor stars ([Fe/H] ...