Ancient Clusters: Milky Way swallowed a dwarf galaxy billions of years ago

Astronomers have found evidence that the Milky Way absorbed a dwarf galaxy during the early stages of its evolution. By analyzing data from the Hubble Space Telescope, researchers identified a group of ancient star clusters that could not have formed within our own galaxy. This discovery extends the known chronology of the Milky Way's mergers back to 11.8 billion years ago. The study was conducted by specialists from the Bologna Observatory of Astrophysics and Space Sciences (OAS) in collaboration with several European institutes. Their findings were published in the journal Nature Astronomy. Tracking the "Stellar Bricks" The Milky Way grew through two primary mechanisms: the birth of new stars from gas and dust clouds and the merger with smaller galaxies. Such mergers increase the galaxy's mass and trigger bursts of star formation by compressing gas. However, identifying these events becomes more difficult as time passes, as the galactic structure erases evidence over billions of years.