Abiotic oxygen atmospheres in habitable planet candidates

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Abiotic oxygen atmospheres in habitable planet candidates

Post by Sirius_Alpha on 11th March 2014, 9:02 pm

Abiotic oxygen-dominated atmospheres on terrestrial habitable zone planets
http://arxiv.org/abs/1403.2713

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.

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