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. 2015 Feb 1;15(2):119–143. doi: 10.1089/ast.2014.1231

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Copyright 2015, Mary Ann Liebert, Inc.

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FIG. 9. — Diffusion-Limited Escape, 1 M_⊕, 1 TO. Similar to Fig. 6 (1 TO) but assuming that the escape of hydrogen is diffusion-limited. This corresponds to planets with slow/ineffective oxygen sinks that retain all the photolytically produced O₂ in their atmospheres. While water loss amounts are generally lower than in the energy-limited case, planets throughout a large fraction of the HZ of M dwarfs are still desiccated. Moreover, the amount of oxygen that builds up is substantially greater than in Fig. 6, since the oxygen cannot escape if the loss of hydrogen is diffusion-limited. Thus, planets that lose 1 TO of water build up ×270=240 bar of O₂ in their atmospheres.

Inline graphic — Diffusion-Limited Escape, 1 M_⊕, 1 TO. Similar to Fig. 6 (1 TO) but assuming that the escape of hydrogen is diffusion-limited. This corresponds to planets with slow/ineffective oxygen sinks that retain all the photolytically produced O₂ in their atmospheres. While water loss amounts are generally lower than in the energy-limited case, planets throughout a large fraction of the HZ of M dwarfs are still desiccated. Moreover, the amount of oxygen that builds up is substantially greater than in Fig. 6, since the oxygen cannot escape if the loss of hydrogen is diffusion-limited. Thus, planets that lose 1 TO of water build up ×270=240 bar of O₂ in their atmospheres.