Observable signatures of wind-driven chemistry with a fully consistent three dimensional radiative hydrodynamics model of HD 209458b (article)
Drummond, B; Mayne, NJ; Manners, J; et al.Carter, A; Boutle, I; Baraffe, I; Hebrard, E; Tremblin, P; Sing, D; Amundsen, D; Acreman, D
Date: 15 March 2018
Journal
Astrophysical Journal Letters
Publisher
American Astronomical Society / IOP Publishing
Publisher DOI
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Abstract
We present a study of the effect of wind-driven advection on the chemical composition of hot Jupiter
atmospheres using a fully-consistent 3D hydrodynamics, chemistry and radiative transfer code, the
Met Office Unified Model (UM). Chemical modelling of exoplanet atmospheres has primarily been
restricted to 1D models that cannot account ...
We present a study of the effect of wind-driven advection on the chemical composition of hot Jupiter
atmospheres using a fully-consistent 3D hydrodynamics, chemistry and radiative transfer code, the
Met Office Unified Model (UM). Chemical modelling of exoplanet atmospheres has primarily been
restricted to 1D models that cannot account for 3D dynamical processes. In this work we couple a
chemical relaxation scheme to the UM to account for the chemical interconversion of methane and
carbon monoxide. This is done consistently with the radiative transfer meaning that departures
from chemical equilibrium are included in the heating rates (and emission) and hence complete
the feedback between the dynamics, thermal structure and chemical composition. In this letter we
simulate the well studied atmosphere of HD 209458b. We find that the combined effect of horizontal
and vertical advection leads to an increase in the methane abundance by several orders of magnitude;
directly opposite to the trend found in previous works. Our results demonstrate the need to include
3D effects when considering the chemistry of hot Jupiter atmospheres. We calculate transmission
and emission spectra, as well as the emission phase curve, from our simulations. We conclude that
gas-phase non-equilibrium chemistry is unlikely to explain the model–observation discrepancy in the
4.5 µm Spitzer/IRAC channel. However, we highlight other spectral regions, observable with the
James Webb Space Telescope, where signatures of wind-driven chemistry are more prominent.
Physics and Astronomy
Faculty of Environment, Science and Economy
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