Identifying Chemically Coherent Stellar Families in the Galactic High-α Disk with Low-Resolution Spectroscopy

Abstract

Identification of chemical substructures in the Galactic high-α disk provides valuable insight into its formation history. In this work, we demonstrate the capability of low-resolution spectroscopy for this purpose by applying DBSCAN clustering to 87,275 red giants in the high-α disk using 18 elemental abundances derived from LAMOST low-resolution spectra (R~1800). We assess the effectiveness of this approach by comparing the clustering results from the low-resolution data with those obtained by applying the same procedure to high-resolution survey abundances and to mock catalogs. These comparisons suggest that, despite the relatively large uncertainties in individual elemental abundances derived from low-resolution spectra, the astrophysical coherence among different elements provides sufficient information to identify chemically coherent families that may share similar enrichment histories without necessarily sharing a common birth environment. After scanning the parameter space of the DBSCAN procedure and merging the results from different parameter combinations, we identify 133 candidate chemical families containing 4,642 unique stars (5.3% of the high-α disk sample). These families exhibit diverse multi-element abundance patterns, with particularly prominent differences in neutron-capture elements at nearly identical [Fe/H] values. These families therefore offer new constraints on the diversity of chemical enrichment pathways and on the assembly history of the high-α disk.