Three Dimensional Radiative Hydrodynamical Simulations of the Highly Irradiated Short Period Exoplanet HD189733b

TL;DR

This paper presents a comprehensive 3D radiative-hydrodynamical simulation of exoplanet HD189733b, accurately modeling atmospheric dynamics, spectra, and phase curves, and highlighting the importance of Rayleigh scattering and condensates.

Contribution

First multi-dimensional simulation including Rayleigh scattering to match optical and UV observations of HD189733b.

Findings

Supersonic winds efficiently advect energy across the planet.

Formation of super-rotating equatorial jets and counter-rotating high-latitude jets.

Good agreement between simulated and observed spectra and phase curves.

Abstract

We present a detailed three-dimensional radiative-hydrodynamical simulation of the well known irradiated exoplanet HD189733b. 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. Calculated transit spectrum agree well with the data from the infrared to the UV including the strong Rayleigh scattering seen at short wavelength, though we slightly under-predict the observations at wavelengths shorter then ~0.6 microns. Our predicted emission spectrum agrees remarkably well at 5.8 and 8 microns, but slightly over-predicts the emission at 3.6 and 4.5 microns when compared to the latest analysis by Knutson et. al (2012). Our simulated IRAC phasecurves agree fairly well with the amplitudes of variations, shape, and phases of minimum and maximum flux. However, we over-predict the peak amplitude at 3.6 and 4.5 microns, and slightly under-predict the location of the phasecurve 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 suggest that including the effects of condensates in simulations as the dominant form of opacity will be very important in future models.