The Galactic habitability

Abstract The Galactic habitable zone is typically defined as the region where metallicity is sufficiently high to enable the formation of planetary systems, allowing Earth-like planets to emerge and potentially sustain life whilst surviving the destructive impact of nearby supernova explosions. Galactic chemical evolution models provide a valuable framework for investigating habitable zones in different environments. In this review, we explore the Galactic habitable zone of the Milky Way’s disc by employing state-of-the-art chemical evolution models, incorporating the likelihood of planetary system formation around M and FGK stars. At a given Galactic age and Galactocentric distance, we show the predicted number of M and FGK stars hosting Earth-like planets (without gas giants) that have survived supernova-induced destruction. The results reveal that the probability of finding terrestrial planets, but not gas giants, differs significantly between M and FGK stars for supersolar [Fe/H] values. When accounting for the disruptive effects of supernovae, the highest concentration of habitable planet-hosting stars for both FGK and M stars is found at a Galactocentric distance of 8 kpc. We also show also results about Andromeda galaxy, and in this case, the maximum number of stars with habitable planets is found towards more external galactic regions, i.e., at 16 kpc from the Galactic centre.