Overview
- Researchers mapped a clear boundary to star birth about 35,000–40,000 light-years from the Galactic Center.
- They found a U-shaped age curve across the disk that hits its youngest point at the boundary, which signals a sharp drop in star-formation efficiency.
- The team measured ages for more than 100,000 giant stars using LAMOST and APOGEE spectra linked to Gaia’s precise distances, then checked the pattern with galaxy simulations.
- Stars beyond the edge likely drifted outward through slow radial migration on near-circular paths, not from a past collision that flung them there.
- What stops star birth at that radius is still unclear, with proposals ranging from the Milky Way’s central bar to an outer-disk warp, and upcoming 4MOST and WEAVE surveys aim to test these ideas.