Application of Fundamental Physical Chemistry to Studies of Exoplanets and Giant Planets

Abstract:

Physical chemistry infuses all aspects of planetary science but is particularly embedded in studies of planetary atmospheres. The physical state of a planetary atmosphere – its temperature structure, physical extent, energy balance, winds, and climate – cannot be understood without a consideration of chemical processes. Chemical constituents control how much stellar radiation is absorbed, where it is absorbed, and how that energy is transferred, all of which drive atmospheric dynamics and control climate. Changes in the physical state of an atmosphere over time often have a chemical origin, whether from geological or biological mechanisms, interior-surface-atmospheric exchange, external impacts, or some other source. Fundamental chemical measurements and calculations are needed to interpret what we see from planetary observations and to constrain and test models of atmospheric processes. Here, I will review a few select cases in which laboratory experiments and fundamental theoretical chemistry calculations have furthered our understanding of giant-planet and exoplanet atmospheres. Although the atmospheres of these planets can be considered exotic by terrestrial standards, the same physical and chemical principles are at play. Recent spacecraft missions and ground-based observations have highlighted interesting atmospheric chemistry on our solar-system giant planets. Concurrently, the field of exoplanet atmospheric science has been growing exponentially, due to an explosion in the number of exoplanets detected in the past decade, and to clever observation strategies that allow exoplanet atmospheres to be characterized. I will explore the role of fundamental chemistry in our investigations of how these atmospheres operate and describe situations in which insufficiencies in our current knowledge of basic chemical parameters hinder our progress.