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

Abrevaya, X. C.; Leitzinger, M.; Oppezzo, O. J.; Odert, P.; Patel, M. R.; Luna, G. J. M.; Forte-Giacobone, A. F. and Hanslmeier, A. (2020). The UV surface habitability of Proxima b: first experiments revealing probable life survival to stellar flares. Monthly Notices of the Royal Astronomical Society: Letters, 494(1) L69-L74.

DOI: https://doi.org/10.1093/mnrasl/slaa037

Abstract

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 CO₂ and N₂ 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.

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• Item ORO ID
• 69674
• Item Type
• Journal Item
• ISSN
• 1745-3933
• Project Funding Details

• Funded Project Name	Project ID	Funding Body
  Modelling and retrieval of martian dust, ice and ozone from ExoMars NOMAD data	ST/P001262/1	UKSA UK Space Agency
  Surface/atmosphere interactions from above and below.	ST/S00145X/1	UKSA UK Space Agency

• Keywords
• Astrobiology; Planets and satellites: terrestrial planets; Planets and satellites: surfaces; Stars: flare; Stars: activity; Ultraviolet: stars
• Academic Unit or School
• Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
  Faculty of Science, Technology, Engineering and Mathematics (STEM)
• Research Group
• ?? space ??
• Copyright Holders
• © 2020 The Author(s)
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