Tuesday 06 Jun 2017A Comparison of Simulated JWST Observations Derived from Equilibrium and Non-Equilibrium Chemistry Models of Gaseous Planets

Sally Blumethal - University of Exeter

4th Floor Interaction Area 11:15-11:45

We investigate the impact of disequilibrium chemistry on exoplanet emission spectra that can be observed by the James Webb Space Telescope (JWST). We compare the dayside emission spectra of three planets like HD 189733b, WASP-80b, and GJ436b, in and out of chemical equilibrium. These three planets were chosen because they span a large range of planetary masses and equilibrium temperatures, from hot and Jupiter-sized to warm and Neptune-sized. We use a one-dimensional disequilibrium chemistry model in which thermochemical kinetics, vertical transport, and photochemistry are taken into account, as well as a one-dimensional, line-by-line radiative transfer model developed especially for hot Jupiters using lines from both HITRAN and HITEMP. We consider the opacities of 16 molecules and collision-induced absorptions from both diatomic hydrogen with itself and with helium. We begin to explore the impact and importance of upper atmospheric heating in our temperature-pressure profiles, and adopt this heating for comparing the effects of temperature, metallicity, and signal-to-noise on simulated JWST spectra. We find the most significant differences due to disequilibrium in CO, CO2, and H2O from 4 to 5 um. A JWST observation with NIRSpec G395M with 5 transits could detect differences due to disequilibrium chemistry in a planet similar to WASP-80b.

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