Diving into the mineralogy and structure of exotic rocky exoplanets

ongoing

Determining the diversity of exoplanets' compositions and structure is fundamental for investigating the Earth's uniqueness. The improvement of ground-based instruments and the launch of new space missions (e.g. JWST) is providing unprecedented information as to exoplanets' masses, radii and atmospheric speciation. However, none of these properties can uniquely constrain the nature of planetary interiors, which dictate their geological evolution. In order to interpret these new observations and identify future exoplanet targets, the implementation of accurate interior models is required. At present, much of our knowledge on exoplanets' interior comes from analogue experiments on Earth-like compositions performed over pressure-temperature-composition spaces relevant for the Solar System. Stellar data, however, has indicated a greater compositional diversity than in our own Solar System, thereby preventing an accurate description of the mineralogy and structure of orbiting planets. ExoDivers aims to bridge the gap between astronomical observations and the interior properties of exoplanets, by investigating the evolution of stable mineralogical assemblages for exotic compositions expected in exoplanetary cores and mantles with pressure and temperature. The experimental bulk compositions will derive from spectroscopic data of observed host stars, providing access to a compositional space that remains yet unstudied. Experiments will be performed to determine the stability of different minerals and refine their thermodynamic properties. These new data will supplement existing databases and will be used to calculate the mantle and core mineralogy of exoplanets. This novel approach obviates the Earth-centric view of exoplanets mineralogy that has characterized the field up to this point and will be implemented to determine, a priori, how variations in the interior affect geological processes, including the possibility of starting convection or activating a dynamo.