Andromeda Galaxy entering ‘middle age’, star formation slowing down

The Andromeda Galaxy appears to be entering its “middle age,” with astronomers finding that its rate of star formation has been steadily declining. Using data from the Hubble Space Telescope, researchers have created the clearest map yet of star formation across most of Andromeda over the last 500 million years.

The study found that the galaxy’s star formation rate has been dropping, with the decline most pronounced over the last 40 million years. Recent star formation is concentrated in Andromeda’s ring structures — and that is also where the slowdown is steepest.

Andromeda, also known as M31, is 2 to 2.5 times wider than the Milky Way. The two galaxies currently have roughly a 50% chance of colliding within the next 10 billion years.

A true-colour image of Andromeda also shows its satellite galaxy M32 visible above and slightly to the left. Scientists say the findings provide new insight into how large spiral galaxies evolve as they age.