Unraveling the Galactic Halo: Identifying Components in the Milky Way’s Stellar Halo

Elliot Y. Davies and his team used a method called Non-negative Matrix Factorization (NMF) to separate the Milky Way’s stellar halo into distinct components based on chemical and spatial data. They identified both in-situ (formed within the Milky Way) and accreted (originating from other galaxies) stars, revealing that the inner halo is dominated by in-situ stars, while accreted stars prevail in the outer regions. Unique structures, such as "Eos" and "Aurora," suggest complex interactions between accreted and in-situ material, reflecting the galaxy's intricate formation history. This study sheds light on how the Milky Way evolved through both internal processes and mergers.