Ancient Milky Way merger revealed by globular-cluster fossils
A Nature Astronomy study uses precise ages and metallicities of Milky Way globular clusters to reconstruct the Galaxy’s early growth, revealing three distinct age–metallicity tracks and an ancient major merger (progenitor Low-energy–Kraken–Heracles) about 12 billion years ago with roughly 500 million solar masses, depositing most material in the inner Milky Way. This refines the Milky Way’s formative timeline and complements JWST views of distant galaxies by tying together fossil stars and early-universe observations.
