The Milky Way has a weird 'edge' where no new stars are born, and the ones that are there just get older the further you walk.
March 20, 2026
Original Paper
The edge of the Milky Way's star-forming disc: Evidence from a 'U-shaped' stellar age profile
arXiv · 2603.18737
The Takeaway
Usually, the further you move from a galaxy's center, the younger the stars are. Astronomers discovered a 'U-shaped' age profile that reveals exactly where our galaxy stops making new stars and where older stars have simply drifted out into the cosmic suburbs.
From the abstract
We leveraged reliable age and distance estimates from LAMOST-DR3 and APOGEE-DR17+AstroNN combined with \gaia\ data to perform a detailed analysis of the stellar age distribution in the Milky Way's (MW) outer disc using giant stars. Selecting stars near the midplane ($|z| 0.9$), we analysed these independent datasets that employed different age-estimation methods. Our stringent kinematic selection criteria effectively exclude halo stars, ensuring that the observed age trends reflect genuine disc