Compositionally driven convection in the interior of Uranus

Abstract:

Uranus shares many similarities with Neptune. Both planets are expected to consist largely of molecular ices, such as water, ammonia, and methane. However, despite many similarities, the two planets differ significantly in their total luminosity. Uranus has been measured to have an unusually low heat flux, which has raised questions about the nature of its internal structure, such as the extent of the convective region within the planet. Here, we study the hypothesis that the nature of convection within the interior of Uranus is primarily chemical, rather than thermal in nature by considering several numerical solutions of each mode of convection. We find that both modes of convection are able to reproduce certain qualitative properties observed in the ice giants, while the means of transporting energy to the surface differ substantially. Better understanding the processes involved may give insights into either the presently existing or previously existing states of the interior of the planet, as well as understanding the consequences of the chemical properties of the materials that make up the ice giant planets.