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Gaia Finds 6,594 Solar Twins, Pointing to a Mass Outward Migration 4–6 Billion Years Ago

Researchers link the age peak to bar-driven outward drift, with the timing and dynamics still unconfirmed.

Overview

  • The two companion studies, published March 12 in Astronomy & Astrophysics, use Gaia DR3 GSP-Spec data to assemble a solar‑twin catalog about 30 times larger than prior samples.
  • The bias‑corrected ages of these Sun‑like stars show a broad peak between 4 and 6 billion years, encompassing the Sun and indicating a coordinated relocation from inner to outer galactic regions.
  • Authors propose the migration coincided with the Milky Way’s central bar taking shape, offering a possible time window for the bar’s assembly and a mechanism to move stars roughly 10,000 light‑years outward.
  • To reconcile models that predict a corotation barrier, the team suggests the barrier formed after the migration event, a sequence that requires further dynamical modeling for confirmation.
  • The findings imply the Solar System may have spent most of its history in the quieter outer disk, a scenario that could have favored the development of life, according to the researchers.