A recent study has shed light on the complex history of the Milky Way galaxy, revealing that it underwent a significant merger event approximately 11.8 billion years ago. This early galactic fusion involved the Milky Way absorbing a smaller dwarf galaxy, adding to its mass and size. The researchers, using advanced telescopes like Hubble and Gaia, analyzed stellar clusters near the Milky Way’s core, determining that the merger introduced a substantial amount of stars, interstellar gas, and dark matter to the galaxy.
Lead author Davide Massari from the National Institute for Astrophysics in Bologna, Italy, described the merger as a relatively peaceful process for the stars but a more explosive one for the gas, likely triggering intense star formation. The study suggests that remnants of the dwarf galaxy, named Low-energy-Kraken-Heracles (LKH), remain within the Milky Way, contributing to its composition.
The Milky Way has been involved in two other major mergers, including the absorption of the Gaia-Sausage-Enceladus dwarf galaxy and the ongoing combination with the Sagittarius dwarf galaxy. Massari emphasized the impact of these mergers on the formation of our solar system and ultimately Earth, highlighting the importance of understanding the galaxy’s past in answering fundamental questions about our origins.