EXOA16

This session will focus on the latest research concerning the most numerous class of exoplanets: small worlds, encompassing rocky planets like Earths and Super-Earths, as well as volatile-rich planets like Mini-Neptunes. We invite contributions that explore the properties, formation pathways, and habitability potential of these key planetary types.

The session also includes contributions that explore the evolution of rocky exoplanets from the perspective of changes to the composition of the Galaxy with time. For example, the inventories of the principal long-lived heat-producing elements, HPEs, 40-K, 235-238-U and 232-Th, are encoded in stellar metallicity, age, and nucleosynthetic history. Yet, the long-term thermal evolution of rocky exoplanets driven by different HPE inventories is often overlooked, even though this evolution is a critical factor in interpreting physical properties including retrieved data for secondary and hybrid atmospheres.

Key areas of interest include:

Atmospheric Characterization: New results on the composition, structure, and dynamics of the atmospheres of small exoplanets, utilizing facilities like JWST and focusing on the volatile content, clouds, and potential detection of biosignatures. This also includes work on secondary and hybrid atmosphere generation.

Mass-Radius Relationship and Interior Structure: Studies that probe the transition between rocky Earths/Super-Earths and volatile-dominated Mini-Neptunes, including interior modeling, precise density measurements, and the physical processes driving atmospheric loss, e.g., photoevaporation.

Formation and Evolution: Theoretical and observational work investigating the birth environments, migration, and long-term evolution of small planets, particularly concerning their initial volatile budget and the influence of the host star. This also includes the long-term thermal evolution of rocky exoplanets driven by different HPE inventories and the expression of different evolutionary tracks as a function of parameters such as system age.

Detection and Demographics: Advances in the discovery and precise characterization of small exoplanets from current and future surveys, e.g., TESS and PLATO, and studies of their occurrence rates and population demographics across different stellar types.

Galactic Chemical Evolution and Rocky Exoplanets: Contributions that report current understanding of how galactic chemical evolution, GCE, processes affect the abundances of the rock-forming elements, Mg, Si, O, Al, Fe, Ca, Na, K, on controls for the abundances of HPEs, and on plausible radiogenic heat budgets of rocky exoplanets across different stellar populations in the Milky Way.

The session encompasses work related to observational, theoretical and experimental studies of small exoplanets, including rocky exoplanets connecting GCE and nucleosynthesis with exoplanetary geodynamics, as well as how these affect magnetic dynamo generation, volcanic activity, and secondary/hybrid atmosphere generation.

The session aims to advance our understanding of the fundamental physics governing the formation and diversity of the most common planets in the Galaxy and their potential for hosting life.