The Milky Way in motion: Mapping the journeys that built the Galactic thin disc — and what lies beyond — Maria Luiza Dantas (PUC)

In the Milky Way, stellar orbits evolve over time, disturbing stars far from their birth radii. In this talk, I will explore radial migration — the process by which stars move across the Galactic disc through interactions with spiral arms, the central bar, and other perturbations — and show how it has shaped the Milky Way’s thin disc structure and history. Using a curated Gaia-ESO sample and a combination of Galactic chemical evolution models and a generalised additive model (GAM), we estimated stellar birth radii and traced systematic migration trends: metal-rich stars from the inner disc tend to move outward, while metal-poor stars from the outer disc often migrate inward. Most thin disc stars are affected by radial migration, with only a minority remaining near their birth radii. We also estimate the Sun’s most probable birth radius at 7.1 ± 0.2 kpc (contrasting with its current position at 8.2 kpc), consistent with previous studies. Beyond the Milky Way, these results offer a framework for interpreting metallicity gradients in other disc galaxies — not as static fossils of formation, but as dynamic records of continuous evolution.