Ariel planetary interiors White Paper

The recently adopted Ariel ESA mission will measure the atmospheric composition
of a large number of exoplanets. This information will then be used to better constrain
planetary bulk compositions. While the connection between the composition of a
planetary atmosphere and the bulk interior is still being investigated, the combination
of the atmospheric composition with the measured mass and radius of exoplanets will
push the field of exoplanet characterisation to the next level, and provide new insights
of the nature of planets in our galaxy. In this white paper, we outline the ongoing
activities of the interior working group of the Ariel mission, and list the desirable
theoretical developments as well as the challenges in linking planetary atmospheres,
bulk composition and interior structure.