Wordsworth, RobinPierrehumbert, Raymond2016-08-152014Wordsworth, Robin, and Raymond Pierrehumbert. 2014. “Abiotic oxygen-dominated atmospheres on terrestrial habitable zone planets.” The Astrophysical Journal Letters 785 (2) (April 1): L20. doi:10.1088/2041-8205/785/2/l20. http://dx.doi.org/10.1088/2041-8205/785/2/L20.2041-8205http://nrs.harvard.edu/urn-3:HUL.InstRepos:27846318Detection 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 \(O_2\) and \(O_3\) alone cannot be regarded as robust signs of extraterrestrial life.en-USJournal Article2016-08-1510.1088/2041-8205/785/2/L20