Astronomers shocked: Milky Way absorbed LKH galaxy over 11 billion years ago

Astronomers have identified evidence that the Milky Way absorbed an ancient dwarf galaxy known as LKH (Low-Energy-Kraken-Heracles) approximately 11.8 billion years ago. This merger occurred earlier than the previously documented collision with the Gaia-Sausage-Enceladus galaxy, providing a new data point for the timeline of the Milky Way's early growth. The discovery was made by an international team of researchers from the Bologna Observatory. The team analyzed ancient globular clusters—dense groups of stars located near the center of the Milky Way. Because these clusters preserve the age and chemical composition of their stars, they serve as indicators of historical galactic events. Method and Evidence Using the Hubble Space Telescope, the researchers measured the metallicity of stars—the concentration of elements heavier than hydrogen and helium. This analysis revealed a group of stars with a chemical profile that differs sharply from the rest of the Galaxy's population, indicating an extraterrestrial origin.