Thermal structure and interior dynamics of the first rocky exoplanets

Abstract

This study is aimed at the interior structure and thermal state of massive rocky exoplanets. We have modeled the interior structure of confirmed super-Earths CoRoT-7b and Kepler-10b, applying a mixing length approach for the radial temperature distribution. 2-D cylindrical mantle convection simulations are performed using the compressible anelastic approximation. These demonstrate the importance of the usage of depth-dependent thermodynamic parameters such as thermal expansivity, conductivity, and density. The calculations indicate that CoRoT-7b and Kepler-10b are similarly composed. Whereas thermal conductivity and density increase with depth by a factor of two, thermal expansivity decreases by more than an order of magnitude across the mantle. The planform of mantle convection is strongly modified in the presence of depth-dependent material properties with hot plumes rising across the whole mantle and cold downwellings assimilated in the mid mantle.