# Brown Dwarf Atmospheres as the Potentially Most Detectable and Abundant Sites for Life

## TL;DR

This paper suggests that the atmospheres of cool brown dwarfs could host more habitable volume than Earth-like planets and proposes observational strategies using JWST to detect signs of life.

## Contribution

It introduces the idea that brown dwarf atmospheres are potentially the most abundant and detectable habitats for life, with specific predictions for observational detection.

## Key findings

- Brown dwarf atmospheres may contain 100 times more habitable volume than Earth.
- Spectral features indicative of life could be detectable with JWST.
- Potential for life detection in free-floating and star-adjacent brown dwarfs.

## Abstract

We show that the total habitable volume in the atmospheres of cool brown dwarfs with effective temperatures of $\sim 250$-$350$ K is possibly larger by two orders of magnitude than that of Earth-like planets. We also study the role of aerosols, nutrients and photosynthesis in facilitating life in brown dwarf atmospheres. Our predictions might be testable through searches for spectral edges in the near-infrared and chemical disequilibrium in the atmospheres of nearby brown dwarfs that are either free-floating or within several AU of stars. For the latter category, we find that the James Webb Space Telescope (JWST) may be able to achieve a signal-to-noise ratio of $\sim 5$ after a few hours of integration time per source for the detection of biogenic spectral features in $\sim 10^3$ cool brown dwarfs.