Inhomogeneous Models of Jupiter and Saturn

The H‐He rich giant planets Jupiter and Saturn serve to test predictions on the high‐pressure behavior of hydrogen and helium. Incorporating the process of H/He phase separation and He rain, or of core erosion, into planet structure and evolution models leads naturally to the assumption of inhomogeneous planetary interiors. In this article we review and discuss recent developments in that regard. It is found that Saturn's luminosity is consistent with a semi‐convective thick shell where the heavy element abundance changes continuously, and that Jupiter's luminosity can as well be explained by a balance between additional gravitational energy and reduced cooling through a He‐rain zone. We present the first Jupiter structure models that include a superadiabatic shell. Using the SCvHi EOS, Jupiter emerges as a mostly homogeneous body apart from a He‐rain zone at a few Megabars. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)