New findings from the Gaia space telescope indicate that the Milky Way’s last major merger with another galaxy was more recent than previously thought, occurring around 2.7 billion years ago rather than 8-11 billion years ago.
The collision, dubbed the Virgo Radial Merger, left “wrinkles” in patterns of the Milky Way’s stars that have been observed by Gaia. Analyzing these wrinkles allows astronomers to date the timing of the merger.
Some stars in the Milky Way’s halo have unusual orbits that were thought to be leftovers from an earlier major merger known as the Gaia-Sausage-Enceladus event around 8-11 billion years ago. But the new Gaia data suggests these stars may have come from the more recent Virgo Radial Merger.
The revised timeline challenges previous models of the Milky Way’s formation that didn’t expect such a large collision so recently. It suggests the Milky Way continues gathering mass through mergers at a later stage than astronomers had proposed.
Further Gaia data could provide more clues about objects associated with prior mergers and help refine our understanding of the Milky Way’s evolutionary history. The article highlights how space telescope discoveries are constantly updating our picture of the galaxy’s past.
Source: Space
