Detection of life on other planets requires identification of biosignatures, i.e., observable planetary properties that robustly indicate the presence of a biosphere.
One of the most widely accepted biosignatures for an Earth-like planet is an atmosphere where oxygen is a major constituent. Here we show that lifeless habitable zone terrestrial planets around any star type may develop oxygen-dominated atmospheres as a result of water photolysis, because the cold trap mechanism that protects H2O on Earth is ineffective when the atmospheric inventory of non-condensing gases (e.g., N2, Ar) is low. Hence the spectral features of O2 and O3 alone cannot be regarded as robust signs of extraterrestrial life.
Robin Wordsworth, Raymond Pierrehumbert (Submitted on 11 Mar 2014)
Comments: 15 pages, 3 figures, accepted for publication in ApJ Letters
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1403.2713 [astro-ph.EP]
(or arXiv:1403.2713v1 [astro-ph.EP] for this version)
Submission history From: Robin Wordsworth [v1] Tue, 11 Mar 2014 19:54:20 GMT (36kb)
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