Iterative model of the chemical and physical interior of differentiated planetesimals
Description
This model consists of two halves, applicable to differentiated planetesimals/asteroids, currently set up to investigate the physical parameters and ferrovolcanic excess pressure generation of asteroid 16 Psyche. Firstly, this model calculates physical and chemical parameters of the core and mantle, based on a bulk composition and its corresponding density as a building block. Input parameters are the mantle density, mantle porosity, bulk composition and its grain density. Mass loss by mantle stripping is calculated to relate the asteroids bulk density with the building block density. Light element partitioning (Ni, P, Si, S, C, and O) between the mantle and the core is calculated according to experimentally derived partitioning equations. These calculations are done in an iterative process as there are feedback loops in the calculation of partitioning parameters and resulting core compositions. Secondly, this model calculates excess pressure generation in the core. This is done by calculating concentric FeNi outer core growth and the resulting trapping of progressively light-element enriched melt. The buoyancy of the light-element enriched melt generates an excess pressure, based on the density difference with the solid outer core and the outer core thickness. This pressure is used to calculate how far through the mantle a column of FeS melt can be carried, and whether ferrovolcanism can thereby be achieved. The current version is set up for modelling asteroid 16 Psyche but can be adapted to other differentiated planetesimals. A user guide is included in the Excel file.