Biofluorescent Worlds I: Global Biological Fluorescence as a Biosignature

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.

arXiv commentPublished in MNRAS. 11 pages, 7 figures

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• Biofluorescent Worlds II. Biological fluorescence induced by stellar UV flares, a new temporal biosignature
• High-resolution reflection spectra for Proxima b and Trappist-1e models for ELT observations
• High-resolution Spectra for a Wide Range of Habitable Zone Planets around Sun-like Stars
• Photosynthetic Fluorescence from Earth-Like Planets around Sun-Like and Cool Stars
• Hot Earth or Young Venus? A nearby transiting rocky planet mystery