HST PHAT wide image of M31

This image is 7,900 light-years across and reveals the Andromeda galaxy's crowded central region. The bright area near the centre of the image is a grouping of stars nestled around the galaxy's black hole. The blue dots sprinkled throughout the image are ultra-blue stars whose population increases around the crowded hub. The blue stars are old Sun-like stars that have prematurely cast off their outer layers of material, exposing their extremely blue-hot cores.