2025RAA....25c5019Z

The 11th data release of the LAMOST survey provides fundamental stellar parameters but lacks detailed abundance measurements for α-elements, which are crucial for understanding stellar populations and Galactic chemical evolution. In this study, we derive the abundances of oxygen (O), magnesium (Mg), silicon (Si), calcium (Ca), and titanium (Ti) for over 6.8 million stars using LAMOST DR11 low-resolution spectra. To ensure reliable measurements, we select 760 open clusters spanning a broad range of ages and apply Monte Carlo sampling for accurate abundance estimates. Additionally, we utilize over 30,000 stars from the GALAH DR4 catalog to train an XGBoost model for extracting α-element abundances from LAMOST DR11 spectra. Bayesian linear regression is employed to analyze the compositional distribution across the Galactic disk and infer chemical gradients as a function of Galactocentric distance. Our results indicate a general increase in chemical abundances with Galactocentric distance, with oxygen showing the steepest gradient. Our results confirm the overall increase of α-element abundances with Galactocentric distance, consistent with previous studies, while minor discrepancies in Mg, Ca, and Ti gradients likely arise from differences in sample selection, observational sensitivity, or Galactic enrichment processes.