Prospects for Life on Temperate Planets Around Brown Dwarfs

TL;DR

This paper assesses the potential for life on planets around brown dwarfs, considering habitable zone duration, photosynthesis needs, and prebiotic conditions, concluding that low-mass brown dwarfs are unlikely to host habitable planets.

Contribution

It provides a comprehensive analysis of habitability prospects around brown dwarfs, integrating factors like habitable zone longevity and biological prerequisites, which is a novel approach.

Findings

Brown dwarfs with mass $ ot hickapprox 30 M_J$ are unlikely to host habitable planets.

Habitable zones around brown dwarfs are temporally shifting, limiting long-term habitability.

Detection of biosignatures on such planets remains challenging but possible.

Abstract

There is growing evidence that brown dwarfs may be comparable to main-sequence stars in terms of their abundance. In this paper, we explore the prospects for the existence of life on Earth-like planets around brown dwarfs. We consider the following factors: (i) the length of time that planets can exist in the temporally shifting habitable zone, (ii) the minimum photon fluxes necessary for oxygenic photosynthesis, and (iii) the lower limits on the fluxes of ultraviolet radiation to drive prebiotic reactions ostensibly necessary for the origin of life. By taking these effects into consideration, we find that it is unlikely for brown dwarfs with masses $\lesssim 30 M_J$ to host habitable planets over geologically significant timescales. We also briefly discuss some of the major biosignatures that might arise on these planets, assess the likelihood of their detection, and highlight some avenues for further study.