Reduced Diversity of Life Around Proxima Centauri and TRAPPIST-1

TL;DR

This paper models biological diversity evolution and suggests that planets around K-dwarfs and G-type stars are more promising for hosting complex life than those around M-dwarfs like Proxima Centauri and TRAPPIST-1.

Contribution

It introduces a simple model linking stellar type, atmospheric erosion, and biological diversity evolution to assess habitability potential.

Findings

Earth-analogs around M-dwarfs are unlikely to be inhabited.

K-dwarfs and G-type stars may host more complex biospheres.

Targeting K-type stars could improve biosignature search success.

Abstract

The recent discovery of potentially habitable exoplanets around Proxima Centauri and TRAPPIST-1 has attracted much attention due to their potential for hosting life. We delineate a simple model that accurately describes the evolution of biological diversity on Earth. Combining this model with constraints on atmospheric erosion and the maximal evolutionary timescale arising from the star's lifetime, we arrive at two striking conclusions: (i) Earth-analogs orbiting low-mass M-dwarfs are unlikely to be inhabited, and (ii) K-dwarfs and some G-type stars are potentially capable of hosting more complex biospheres than the Earth. Hence, future searches for biosignatures may have higher chances of success when targeting planets around K-type stars.