Overview
- The peer‑reviewed Hubble analysis published this week reports that Andromeda’s star‑formation rate has dropped from about one solar mass per year 500 million years ago to roughly 0.2 solar masses per year today.
- Researchers reconstructed this trend by age‑dating nearly 200 million individual stars from Hubble surveys that covered roughly two‑thirds of M31’s disk, treating stellar color as a clock for past star birth.
- Most of the recent decline is concentrated in a ring about 32,000 light‑years from the galaxy’s center, whose fading activity largely accounts for the overall slowdown.
- A local drop in star formation beginning around 60 million years ago near the small companion M32 suggests a past encounter might have played a role, but the study says a causal link is not yet confirmed because M32’s true 3‑D orbit is uncertain.
- Teams will mine archival Hubble data and use the Nancy Grace Roman Space Telescope’s much wider near‑infrared maps to cover Andromeda’s full disk and halo and to test whether past interactions or internal winding explain the decline.