Galactic archaeologists find stars in the Milky Way came from another galaxy 12 billion years ago
The Milky Way contains a fossil record of galaxies it has absorbed.
Galactic astronomers have uncovered evidence that stars in the Milky Way originated from a galaxy that merged with our own 12 billion years ago. Led by Davide Massari from the Astrophysics and Space Science Observatory of Bologna, Italy, the team employed precise ages of dense clusters of stars to determine the age, mass, and evolution of the ancient galaxy that merged with the Milky Way.
This period, marking the galaxy's formative years, is particularly challenging to reconstruct due to its early stage. The Milky Way, like other galaxies, grew through the merger of smaller systems, leaving behind a fossil record of these events. The Gaia–Sausage–Enceladus, or GSE, merger, which occurred around 10 billion years ago, is one of the clearest chapters in this history.
However, determining earlier merger events has been more difficult. By studying globular clusters - dense groups of hundreds of thousands of stars that formed simultaneously - the researchers were able to better understand the early merger event, known as Low-energy–Kraken–Heracles (LKH). This event occurred roughly 1.8 billion years before GSE and involved a galaxy with a mass similar to the Milky Way.
By combining this new evidence with observations of distant galaxies, astronomers are piecing together a more detailed history of the Milky Way's formation and growth.
Written by urgent.news from The Conversation AU's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
