Hakim, Kaustubh

Seminar presented at ARIES, Nainital, India on 2024-04-23

Abstract: Exoplanet science is a new, exponentially growing field of astronomy challenging the theoretical understanding of planets. Planet occurrence studies focusing on the size distribution of planets have revealed three major classes of exoplanets, gas giants, gas dwarfs (sub-Neptunes), rocky exoplanets (super-Earths and smaller planets). Unlike gas giants, super-Earths and sub-Neptunes are dominated by their rocky interiors. This decade is witnessing a major shift from the atmospheric characterisation of gas giant exoplanets to their smaller counterparts. In the absence of direct measurements of deep interiors, the following three astronomical windows reveal rocky interiors. Mass-radius measurements inform about bulk planet composition; atmospheric characterisation reveals atmospheric composition and host-star refractory elemental abundances give potential estimates of interior composition. While the observations of atmospheres of sub-Neptunes and rocky exoplanets keep growing, the understanding of chemical diversity in planetary interiors and interior-atmosphere interactions is more vital than ever. In this overview talk, I will focus on rocky exoplanet interiors and evolution from the perspective of chemical and physical diversity. The inventory of refractory elements largely determines the interior composition, mineralogy and structure. The inventory of volatile elements further influences the interior evolution and atmospheric chemistry. I will discuss the role of exoplanet interiors in the composition of atmospheres, including processes such as geochemical cycling and outgassing. Going forward, we will need to develop a thorough understanding of planetary mineralogy, material properties and processes that occur outside the physical and chemical realms of Earth and planetary bodies in the Solar System with the help of theoretical models and laboratory experiments.

Funding: FED-tWIN/STELLA/Prf-2021-022