A recent study has shed light on the complex evolution of the Milky Way galaxy, which is home to numerous stars, including our sun. Researchers have uncovered evidence of a significant event in the galaxy’s past – the absorption of a smaller galaxy approximately 11.8 billion years ago, when the universe was in its early stages. This merger, marking the earliest-known galactic interaction for the Milky Way, highlights how the galaxy expanded not only through its own star formation but also by assimilating smaller galaxies drawn in by its gravitational pull.
The smaller galaxy involved in the merger was classified as a dwarf galaxy, distinguishing it from larger galaxies like the Milky Way. It is estimated that this dwarf galaxy contained stars equivalent to 500 million times the mass of the sun at the time of the merger, making it roughly a quarter of the Milky Way’s size at that point.
By utilizing data from the Hubble and Gaia telescopes, researchers examined stellar clusters within the inner 20,000 light-years of the Milky Way, analyzing their age, composition, and trajectory. These stars became part of the Milky Way following a galactic merger that occurred around two billion years after the Big Bang.
The study, published in the journal Nature Astronomy and led by astrophysicist Davide Massari, has confirmed the Milky Way’s first merger event during its early stages. The research suggests that the merger injected a substantial amount of stars, interstellar gas, and dark matter into the Milky Way, fostering star formation.
According to Massari, the merger was “peaceful” in terms of stars, with no direct collisions, but the interaction of gases from both galaxies likely triggered a burst of star formation. The Milky Way has been involved in two other major mergers in the past, further influencing its development and potentially impacting the formation of our solar system.
Understanding the Milky Way’s history, as revealed through these mergers, offers valuable insights into the origins of our cosmic neighborhood and the fundamental question of our existence.