Details

Autor(en) / Beteiligte

• Harman, C. E.
• Felton, R.
• Hu, R.
• Domagal-Goldman, S. D.
• Segura, A.
• Tian, F.
• Kasting, J. F.

Titel

Abiotic O 2 Levels on Planets around F, G, K, and M Stars: Effects of Lightning-produced Catalysts in Eliminating Oxygen False Positives

Ist Teil von

• The Astrophysical journal, 2018-10, Vol.866 (1), p.56

Erscheinungsjahr

2018

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• Abstract Over the last few years, a number of authors have suggested that, under certain circumstances, molecular oxygen (O 2 ) or ozone (O 3 ) generated by abiotic processes may accumulate to detectable concentrations in a habitable terrestrial planet’s atmosphere, producing so-called “false positives” for life. But the models have occasionally disagreed with each other, with some predicting false positives, and some not, for the same apparent set of circumstances. We show here that photochemical false positives derive either from inconsistencies in the treatment of atmospheric and global redox balance or from the treatment (or lack thereof) of lightning. For habitable terrestrial planets with even trace amounts of atmospheric N 2 , NO produced by lightning catalyzes the recombination of CO and O derived from CO 2 photolysis and should be sufficient to eliminate all reported false positives. Molecular oxygen thus remains a useful biosignature gas for Earth-like extrasolar planets, provided that the planet resides within the conventional liquid water habitable zone and has not experienced distinctly non-Earth-like, irrecoverable water loss.