On the Surface Heating of Synchronously Spinning Short‐Period Jovian Planets

We consider the atmospheric flow on short-period extra-solar planets throughtwo-dimensional numerical simulations of hydrodynamics with radiation transfer.One side is always exposed to the irradiation from the host star. The other isalways in shadow. The temperature of the day side is determined by theequilibrium which the planetary atmosphere establishes with stellar radiation.Part of the thermal energy deposited on the day side is advected to the nightside by a current. The radiation transfer, the night-side temperaturedistribution and by this the spectroscopic signature of the planet aresensitive functions of the atmospheric opacity. If the atmosphere containsgrains with an abundanceand size distribution comparable to that of theinterstellar medium, shallow heating occurs on the day side and the night sidecools well below the day side. The temperature difference decreases as theabundance of grains is reduced. A simple analytic model of the dissipation ofthe circulation flow and associated kinetic heating is considered. This heatingeffect occurs mostly near the photosphere, not deep enough to significantlyaffect the size of planets. We show that the surface irradiation suppressesconvection near the photospheric region on the day side. In some casesconvection zones appear near the surface on the night side. This structuralmodification may influence the response and dissipation of tidal disturbancesand alter the circularization and synchronization time scales.Comment: 24 pages, 8 figures, submitted to Ap