ABSTRACT:
One of the most significant discoveries in exoplanet science is that sub-Neptunes, planets between Earth and Neptune in size, appear to be the most abundant type of planet in the Galaxy. With no Solar System analogue, fundamental questions about their structure, formation and evolution remain unsolved. With JWST, we can now measure the chemical compositions of the upper atmospheres of sub-Neptunes with unprecedented precision. In this talk, I will show how these atmospheric inferences can be used to constrain internal structure and test theories of key processes, such as interactions between an atmosphere and an underlying magma ocean. I will present applications of coupled atmosphere-interior models to a number of planets which have been observed with JWST, providing new insight into their possible nature. I will also discuss some of the challenges associated with inferring atmospheric properties from spectroscopic observations, and present methods that can be used to ensure robustness of any claims made about the presence of specific chemical species or physical phenomena.
