A recent study has shed light on the complex evolution of the Milky Way galaxy, revealing a significant event from its early history. Scientists studying star clusters near the Milky Way’s core have uncovered evidence of a galactic merger that occurred approximately 11.8 billion years ago when the universe was still young.
The research suggests that a smaller dwarf galaxy, known as Low-energy-Kraken-Heracles (LKH), was assimilated by the Milky Way, adding approximately 500 million times the mass of the sun to our galaxy. This merger marked a crucial milestone in the Milky Way’s development, demonstrating how it grew not only through internal star formation but also by incorporating smaller galaxies within its gravitational influence.
To investigate this merger, researchers utilized data from the Hubble and Gaia telescopes to analyze stellar clusters within the Milky Way’s innermost 20,000 light-years. These clusters, each containing hundreds of thousands of stars, provided insights into the age, composition, and trajectory of the stars involved in the merger event.
According to the lead author of the study, astrophysicist Davide Massari, this discovery represents the earliest-known galactic merger experienced by the Milky Way. The merger process, though peaceful for the stars involved, likely triggered a burst of star formation due to the collision of gas from both galaxies.
The Milky Way has a rich history of galactic interactions, having merged with two other significant galaxies in the past. These mergers, including the absorption of Gaia-Sausage-Enceladus and the ongoing combination with the Sagittarius dwarf galaxy, have played a role in shaping the Milky Way as we know it today.
Understanding these galactic mergers not only contributes to our knowledge of the Milky Way’s formation but also provides insights into the origins of our solar system and Earth. By reconstructing the galaxy’s past, researchers aim to address fundamental questions about our cosmic origins.