Hubble’s deep dive shows Andromeda winding down its star formation

Using two major Hubble surveys mapping roughly two-thirds of Andromeda’s disk, researchers traced star formation over the past 500 million years and found the galaxy’s rate has declined from about 1 solar mass per year to roughly 0.2 per year, with most recent star formation concentrated in a ring about 32,000 light-years from the center. This winding-down pattern suggests Andromeda is returning to a quiescent state after a past starburst likely tied to a merger with its companion M32; its collision with the Milky Way, about 5 billion years away, remains uncertain. The work, published July 27, 2026 in The Astrophysical Journal, underscores Hubble’s detailed view and points to broader surveys by NASA’s Roman Space Telescope.