Identifying Exoplanet Atmospheric Loss by Observing Isotopologue Bands With the James Webb Space Telescope
When: November 20, 2018 3PM PST
Terrestrial planets orbiting M dwarfs may soon be observed with the James Webb Space Telescope (JWST) to characterize their atmospheric composition and search for signs of habitability or life. These planets may undergo significant atmospheric and ocean loss due to their host stars superluminous pre-main-sequence phase, which may leave behind abiotically-generated oxygen, a false positive for the detection of life. Determining if ocean loss has occurred will help assess potential habitability and whether or not any O2 detected is biogenic. In the Solar System, differences in isotopic abundances have been used to infer the history of ocean loss and atmospheric escape (e.g. Venus, Mars). I will show how H2O and CO2 isotopologue measurements using transit transmission spectra of terrestrial planets around late-type M dwarfs like TRAPPIST-1 are possible with JWST, if the escape mechanisms and resulting isotopic fractionation are as severe as Venus, and could be considered as indicators of ocean loss and atmospheric escape, as they have in our Solar System.