Ceres – Neither a porous nor salty ball

This study explores the geophysical implications of two compositional models recently proposed for Ceres, which assume that the dwarf planet is a homogeneous mixture of chondritic material devoid with free water. In order to reproduce Ceres’ density, the rock density has to be offset by the presence of porosity and/or an abundance of hydrated salts resulting from the extensive hydration and oxidation of the chondritic material. Thermal modeling shows that a mixture of hydrated minerals is bound to compact and partly dehydrate as a consequence of long-lived radioisotope decay heat. The resulting interior structure is differentiated in a silicate-rich core and water-rich shell, with little porosity. Hence, this study confirms previous suggestion that Ceres contains a large fraction of free water.