Potential impact of the Sagittarius dwarf galaxy on the formation of young O-rich stars

• DOI: 10.1038/s41467-025-56550-1
• Publication Date: 2025-02-12T16:07:37Z
• Authors: Tiancheng Sun; Shaolan Bi; Xunzhou Chen; Yuqin Chen; Yuxi Lucy Lu; Chao Liu; Tobias Buck; Xianfei Zhang; Tanda Li; Yaguang Li; Yaqian Wu; Zhishuai Ge; Lifei Ye
• Keywords: Sagittarius; Dwarf spheroidal galaxy

The Milky Way underwent significant transformations in its early history, characterised by violent mergers and satellite galaxy accretion. However, recent observations reveal notable star formation events over the past 4 Gyr, likely triggered perturbations from Sagittarius dwarf galaxy. Here, we present chemical signatures of this accretion event, using [Fe/H] (metallicity) [O/Fe] (oxygen abundance) ratios thin-disc stars. In normalised age-metallicity plane, identify a discontinuous V-shape structure at $${{{{\rm{z}}}}}_{\max }$$ (maximum vertical distance disc plane) < 0.4 kpc local disc, interrupted burst between 2 Gyr ago. This event is increase oxygen abundance, resulting distinct gradient young O-rich These stars have larger birth radii, indicating outer followed radial migration to Solar neighbourhood. Simulations late infall suggest that passage may contributed observed abundance disc. Enhanced rates our during 2–4 known survey data, linked galaxy's passage. authors show an (O) period, suggesting contribution O abundances.