The UV surface habitability of Proxima b: first experiments revealing probable life survival to stellar flares

Abstract

We use a new interdisciplinary approach to study the UV surface habitability of Proxima $b$ under quiescent and flaring stellar conditions. We assumed planetary atmospheric compositions based on CO${}_2$ and N${}_2$ and surface pressures from 100 to 5000 mbar. Our results show that the combination of these atmospheric compositions and pressures provide enough shielding from the most damaging UV wavelengths, expanding the "UV-protective" planetary atmospheric compositions beyond ozone. Additionally, we show that the UV radiation reaching the surface of Proxima $b$ during quiescent conditions would be negligible from the biological point of view, even without an atmosphere. Given that high UV fluxes could challenge the existence of life, then, we experimentally tested the effect that flares would have on microorganisms in a "worst-case scenario" (no UV-shielding). Our results show the impact that a typical flare and a superflare would have on life: when microorganisms receive very high fluences of UVC, such as those expected to reach the surface of Proxima $b$ after a typical flare or a superflare, a fraction of the population is able to survive. Our study suggests that life could cope with highly UV irradiated environments in exoplanets under conditions that cannot be found on Earth.

arXiv commentAccepted for publication in MNRAS Letters

References in corpus (18)

• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• The Effect of a Strong Stellar Flare on the Atmospheric Chemistry of an Earth-like Planet Orbiting an M dwarf
• The Habitability of Proxima Centauri b: II: Environmental States and Observational Discriminants
• UV Surface Environment of Earth-like Planets Orbiting FGKM Stars Through Geological Evolution
• The Surface UV Environment on Planets Orbiting M-Dwarfs: Implications for Prebiotic Chemistry & Need for Experimental Follow-Up
• UV habitable zones around M stars
• The First Naked-Eye Superflare Detected from Proxima Centauri
• MOST Observations of our Nearest Neighbor: Flares on Proxima Centauri
• The Upper Atmospheres of Terrestrial Planets: Carbon Dioxide Cooling and the Earth's Thermospheric Evolution
• UV Surface Habitability of the TRAPPIST-1 System
• Extreme hydrodynamic losses of Earth-like atmospheres in the habitable zones of very active stars
• Ultraviolet Radiation Constraints around the Circumstellar Habitable Zones
• Flaring activity of Proxima Centauri from TESS observations: quasi-periodic oscillations during flare decay and inferences on the habitability of Proxima b
• The detection of M-dwarf UV flare events in the GALEX data archives
• The habitability and detection of Earth-like planets orbiting cool white dwarfs
• Lessons from early Earth: UV surface radiation should not limit the habitability of active M star systems
• Superflare UV flashes impact on Kepler-96 system: a glimpse of habitability when the ozone layer first formed on Earth

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• Properties of flares and CMEs on EV Lac: Possible erupting filament
• Orbital inclination and mass of the exoplanet candidate Proxima c
• A revised lower estimate of ozone columns during Earth's oxygenated history
• Activity of TRAPPIST-1 analogue stars observed with TESS
• Correcting Stellar Flare Frequency Distributions Detected by TESS and Kepler
• Eta-Earth Revisited II: Deriving a Maximum Number of Earth-like Habitats in the Galactic Disk
• Bridging High-Density, Electron Beam Coronal Transport and Deep Chromospheric Heating in Stellar Flares
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