Atmospheric circulation and tides of “51 Pegasus b-like” planets

We examine the properties of the atmospheres of extrasolar giant planets at orbital distances smaller than 0.1 AU from their stars. We show that these “51 Peg b-like” planets are rapidly synchronized by tidal interactions, but that small departures from synchronous rotation can occur because of fluid-dynamical torques within these planets. Previous radiative-transfer and evolution models of such planets assume a homogeneous atmosphere. Nevertheless, we show using simple arguments that, at the photosphere, the day-night temperature difference and characteristic wind speeds may reach ~500 K, and ~2 km s-1, respectively. Substantial departures from chemical equilibrium are expected. The cloud coverage depends…

• NS
  National Science Foundation