Biofluorescent Worlds I: Global Biological Fluorescence as a Biosignature

TL;DR

This paper proposes biofluorescence as a novel biosignature for detecting complex life on exoplanets orbiting F stars, based on simulated observable signals caused by surface fluorescence.

Contribution

It introduces biofluorescence as a new surface biosignature and models its potential detectability on exoplanets orbiting F stars.

Findings

Biofluorescence can produce detectable signals in the visible spectrum.

Exoplanets with fluorescent biospheres may exhibit characteristic surface colors.

Simulations suggest upcoming telescopes could observe these biosignatures.

Abstract

In this paper, we analyze a new possible biological surface feature for habitable worlds orbiting other stars: biofluorescence. High ultraviolet (UV) and blue radiation fluxes drive the strongest biofluorescence in terrestrial fluorescent pigments and proteins. F stars emit more blue and UV radiation than the Sun, while planets and exomoons orbiting such stars remain in the habitable zone for 2-4 Gyr; a timespan that could allow a complex biosphere to develop. Therefore we propose biofluorescence as a new surface biosignature for F star planets. We investigate how the extra emission from surface fluorescence could cause observable signals at specific wavelengths in the visible spectrum. Using the absorption and emission characteristics of common coral fluorescent pigments and proteins, we simulate the increased emission at specific visible wavelengths caused by strong fluorescence, accounting for the effects of different (non-fluorescent) surface features, atmospheric absorption and cloud-cover. Our model shows that exoplanets with a fluorescent biosphere could have characteristic surface colours that allow the presence of surface life to be inferred from observations with upcoming telescopes.