Three-dimensional radiative-hydrodynamical simulations of the highly irradiated short-period exoplanet HD 189733b

Abstract

We present a detailed three-dimensional radiative-hydrodynamical simulation of the well-known irradiated exoplanet HD 189733b. Our model solves the fully compressible Navier–Stokes equations coupled to wavelength-dependent radiative transfer throughout the entire planetary envelope. We provide detailed comparisons between the extensive observations of this system and predictions calculated directly from the numerical models. The atmospheric dynamics is characterized by supersonic winds that fairly efficiently advect energy from the dayside to the nightside. Super-rotating equatorial jets form for a wide range of pressures from 10−5 to ∼10 bars, while counter-rotating jets form at higher latitudes. The calculated transit spectrum agrees well with the data from the infrared to the ultraviolet (UV) including the strong Rayleigh scattering seen at short wavelength, though we slightly underpredict the observations at wavelengths shorter than ∼ 0.6 μm. Our predicted emission spectrum agrees remarkably well at 5.8 and 8 μm, but slightly overpredicts the emission at 3.6 and 4.5 μm when compared to the latest analysis by Knutson et al. Our simulated Infrared Array Camera (IRAC) phase curves agree fairly well with the amplitudes of variations, shape, and phases of minimum and maximum flux. However, we overpredict the peak amplitude at 3.6 and 4.5 μm, and slightly underpredict the location of the phase curve maximum and minimum. These simulations include, for the first time in a multi-dimensional simulation, a strong Rayleigh scattering component to the absorption opacity, necessary to explain observations in the optical and UV. The agreement between our models and observations suggests that including the effects of condensates in simulations as the dominant form of opacity will be very important in future models.