A recent study has shed light on the complex evolution of the Milky Way galaxy. Researchers have uncovered evidence indicating that the Milky Way absorbed a smaller galaxy around 11.8 billion years ago, during a time when the universe was still relatively young. This galactic merger, the earliest known in the Milky Way’s history, demonstrates that the galaxy not only formed its own stars but also grew by incorporating smaller galaxies within its gravitational pull.
The smaller galaxy involved in the merger was classified as a dwarf galaxy, containing stars with a mass equivalent to about 500 million times that of the sun at the time of the event. By studying stellar clusters near the Milky Way’s center using the Hubble and Gaia telescopes, researchers were able to analyze the age, composition, and trajectory of these stars, which now form part of the Milky Way.
This merger occurred approximately two billion years after the Big Bang and contributed significantly to the Milky Way’s early growth. The research, led by astrophysicist Davide Massari from the National Institute for Astrophysics in Italy, was published in Nature Astronomy.
According to Massari, the merger introduced a large volume of stars, interstellar gas, and dark matter into the Milky Way, fueling star formation. While the merger was relatively peaceful for the stars involved, it triggered the formation of many new stars due to the collision of gases from the two galaxies.
The Milky Way has been involved in two other major mergers in its history, including the absorption of the Gaia-Sausage-Enceladus dwarf galaxy and ongoing interactions with the Sagittarius dwarf galaxy. These mergers have played a crucial role in shaping the Milky Way and have influenced the formation of our solar system and Earth.
Understanding the Milky Way’s past through these mergers contributes to answering fundamental questions about the origins of our galaxy and our place in the universe.
