Schaefer, LauraWordsworth, RobinBerta-Thompson, ZachorySasselov, Dimitar2021-04-142016-09-22Schaefer, Laura, Robin Wordsworth, Zachory Berta-Thompson, Dimitar Sasselov. "Predictions of the Atmospheric Composition of GJ 1132b." ApJ 829, no. 2 (2016): 63. DOI: 10.3847/0004-637x/829/2/631538-4357https://nrs.harvard.edu/URN-3:HUL.INSTREPOS:37367267GJ 1132b is a nearby Earth-sized exoplanet transiting an M dwarf, and is among the most highly characterizable small exoplanets currently known. In this paper, we study the interaction of a magma ocean with a water-rich atmosphere on GJ 1132b and determine that it must have begun with more than 5 wt% initial water in order to still retain a water-based atmosphere. We also determine the amount of O2 that can build up in the atmosphere as a result of hydrogen dissociation and loss. We find that the magma ocean absorbs at most ~10% of the O2 produced, whereas more than 90% is lost to space through hydrodynamic drag. The most common outcome for GJ 1132b from our simulations is a tenuous atmosphere dominated by O2, though, for very large initial water abundances, atmospheres with several thousands of bars of O2 are possible. A substantial steam envelope would indicate either the existence of an earlier H2 envelope or low XUV flux over the system's lifetime. A steam atmosphere would also imply the continued existence of a magma ocean on GJ 1132b. Further modeling is needed to study the evolution of CO2 or N2-rich atmospheres on GJ 1132b.en-USSpace and Planetary ScienceAstronomy and AstrophysicsJournal Article2021-04-1410.3847/0004-637x/829/2/63