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

Abstract

We present detailed three-dimensional radiative-hydrodynamical models 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 ∼ 0.6µm. Our predicted emission spectrum agrees remarkably well at 5.8 and 8µm, but slightly over-predicts the emission at 3.6 and 4.5µm 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 3.6µm and 4.5µm, 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.

Accuracy tests of radiation schemes used in hot Jupiter global circulation models

“…The bands were selected as in Showman et al (2009), see Table 4. Improved schemes utilising mean absorption coefficients exist, but we limit our discussion to the approach used by Dobbs-Dixon & Agol (2013) and compare its accuracy to a full correlated-k treatment. For this purpose, we show in Sect.…”

Results from a set of three-dimensional numerical experiments of a hot Jupiter atmosphere

“…Therefore, although much progress has been made (and much more can yet be made) using 1D models, 3D models are required to truly unpick the observations, and extract robust physical meaning. E-mail: nathan@astro.ex.ac.uk Several GCMs (or similar models) with varying levels of sophistication have been applied to hot Jupiters (see for example Cooper & Showman 2005;Cho et al 2008;Menou & Rauscher 2009;Rauscher & Menou 2010;Heng et al 2011;Dobbs-Dixon & Agol 2013;Parmentier et al 2013;Showman et al 2015;Helling et al 2016;Kataria et al 2016;Lee et al 2016), including our own adaptation of the Met Office GCM termed the Unified Model (UM) (Mayne et al 2014a,b;Amundsen et al 2014;Helling et al 2016;Amundsen et al 2016Amundsen et al , 2017Boutle et al 2017). However, much of the progress has been driven by application of a single GCM, the SPARC/MITgcm.…”

The unified model, a fully-compressible, non-hydrostatic, deep atmosphere global circulation model, applied to hot Jupiters

“…Despite the exotic nature of the flow regime, the adaptation of GCMs to hot Jupiters has met with success as, for example, several models have been able to demonstrate that offsets in the hot spot are consistent with redistribution from zonal (longitudinal direction) winds (Showman et al 2009;Dobbs-Dixon & Lin 2008;Dobbs-Dixon 2009). The progress of the modelling has been reviewed in Showman et al (2008 and a useful summary of the different approaches taken can be found in Dobbs-Dixon & Agol (2013).…”

“…However, the approximations involved in the primitive equations neglect the vertical acceleration of fluid parcels, and the effect of the vertical velocity on the horizontal momentum. More complete dynamical models, solving the full Navier-Stokes equations, have been applied to hot Jupiters by Dobbs-Dixon & Lin (2008), Dobbs-Dixon (2009), Dobbs-Dixon et al (2010), Dobbs-Dixon & Agol (2013), but these models include a radiative transfer scheme more simplified than the method of Showman et al (2009). Dobbs-Dixon et al (2010) includes frequency dependent radiative transfer via the introduction of only three opacity bins (and generally runs for short elapsed model times).…”