Atmospheric Dynamics on Unevenly Irradiated Jovian Planets

Jonathan Langton (UC Santa Cruz)

The increasingly rapid pace of the discovery of extrasolar planets has brought to light a number of worlds with properties vastly different from those in our own solar system. Dramatic examples of this variety are provided by a class of planets with highly eccentric (e > 0.3) orbits, with very close (a(1-e) < 0.05 AU) periastron passages. On these planets, the subsolar irradiance varies by a factor of 3 to 1000, typically reaching ~10⁶ W/m² at periastron.

I will present the results of two-dimensional hydrodynamic simulations of the upper atmospheres of these planets. The flow geometry is complex, turbulent, and primarily driven by the sudden influx of energy at periastron. I will focus attention on 4 particularly interesting planets. HD 80606 b (e=0.9321) has the largest eccentricity of any planet yet discovered. HAT-P-2 b (e=0.507) presents a particularly promising observational target due to the large infrared flux variation we predict, and due to the fact that it transits its parent star. HD 17156 b (e=0.67) also transits. Finally, HD 37605 b (e=0.737), while not particularly suitable for observation, occupies an especially interesting dynamical regime, with persistent circumpolar vortices shielding their interiors from most of the periastron heating.