A Twisted, Two-Break Milky Way Halo: What DESI Reveals
DESI observations of distant K giant stars reveal that the Milky Way’s stellar halo is triaxial, tilted, and twists with distance, switching from oblate and disk aligned inside 30 kpc to prolate and nearly perpendicular outside. The halo’s density shows two major breaks linked to past mergers, including Gaia Sausage Enceladus and the Large Magellanic Cloud. Several overdensities and metal poor stars further trace the Galaxy’s complex assembly history.
Chasing a Galactic Starburst: Clues from the Milky Way’s High Proper-Motion Stars
This study uncovers a unique group of stars, called LAHN stars, that likely formed during a major merger between the Milky Way and the Gaia-Sausage/Enceladus galaxy. Their distinct chemical signatures and orbits suggest a burst of star formation triggered by the collision. These stars help reveal how such events shaped the Milky Way’s early evolution.
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.