Thermo-chemical evolution of ice-silicate bodies: Application to Ceres

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Ceres is the largest body in the asteroid belt having the radius of ~470 km. Considered as a protoplanet along with Pallas and Vesta, Ceres can be seen as one of the remaining examples of the intermediate stages of planetary accretion, which additionally is considerably different from most asteroids. Its low bulk density of about 2077 kg/m3 suggests a global ice mass fraction of 17 - 27 % if the average porosity is negligible. Furthermore, it is suggested that Ceres differentiated early in its evolution due to heating of short-lived radioactive elements such as 26Al and consists of a silicate-iron core and an upper ice layer.In this project, we intend to study the thermo-chemical evolution of Ceres with a new numerical model. Ceres is the second target of the Dawn spacecraft, which will enter its orbit in spring 2015. Dawn will most certainly provide data of the shape, density, structure, surface and composition of Ceres; thus, numerical modelling prior to and after the arrival at the target will allow to keep pace with the observation and help to establish the most likely evolution scenario. To study the thermo-chemical evolution of Ceres we will consider the various processes relevant for icy bodies like amorphous to crystalline ice transition, melting of ice and hydrothermal convection, hydration and dehydration reactions of the silicate, differentiation of ice and silicates, silicate and possible iron melting. The aim is to find likely evolution scenarios and interior structures of this body depending on its composition, formation time relative to the calcium-aluminium-rich inclusions (CAIs) and accretion duration. We will further provide a better understanding of other icy bodies like icy asteroids and satellites.