Study Dates Milky Way's GSE Collision to 11 Billion Years Ago, Triggering Starburst
Updated
Updated · starlust.org · May 19
Study Dates Milky Way's GSE Collision to 11 Billion Years Ago, Triggering Starburst
4 articles · Updated · starlust.org · May 19
ICCUB and IEEC researchers say the Milky Way’s last major merger likely struck about 11 billion years ago, earlier than many previous estimates and tied to the Gaia-Sausage-Enceladus event.
Auriga simulations and observational data showed major collisions can partly or completely destroy stellar discs, meaning the onset of coherent disc rotation likely marked the galaxy’s recovery rather than its first formation.
That revised timeline matches a peak in Milky Way star-cluster formation, supporting the idea that the impact compressed gas and set off a galaxy-wide burst of star formation — a “galactic firework.”
The work builds on Gaia’s 2018 detection of unusual stellar motions that pointed to the merger and sharpens how astronomers reconstruct the Milky Way’s early evolution while awaiting deeper views from JWST and ALMA.
If our galaxy was violently reset, do other spiral galaxies also hide a history of destruction and rebirth?
How does invisible dark matter act as the architect for rebuilding galaxies after catastrophic cosmic collisions?
What secrets does a tiny star cluster hold about the lost galaxy that rebuilt the Milky Way?
11 Billion Years Ago: The Galactic Collision That Transformed the Milky Way’s Structure and Chemistry
Overview
A groundbreaking study published in May 2026 reveals that about 11 billion years ago, the Milky Way experienced a catastrophic collision known as the Gaia-Sausage-Enceladus (GSE) merger. This violent event fundamentally reshaped our galaxy by largely destroying its original rotating stellar disk and resetting its structure. The impact of the merger triggered a 'stellar firework,' dramatically increasing star formation rates and leading to the creation of new stars and clusters. These findings provide unprecedented insight into the Milky Way's turbulent early history and help explain how its current structure came to be.