Internal fractionation of atmosphere-forming volatile elements on low-mass exoplanets

Low-mass exoplanets in a partially molten state open a novel window into key processes that shape the earliest, high-temperature evolutionary regimes of rocky worlds and their long-lived climate states. In this talk I will outline how magma ocean dynamics and core-mantle segregation influence the coupled interactions between largely molten interiors and volatile envelopes. The physical and chemical coupling between magma layers and their outgassing atmospheres can fractionate the dominant volatiles observable in the atmosphere to a degree that is testable with current instrumentation. As a key example, nitrogen species can be suppressed in the atmosphere if the volatile envelope is in direct contact with a chemically reduced molten interior. Using the high-priority targets K2-18 b, 55 Cnc e, GJ 367 b, GJ 468 b, and TOI-561 b, I will outline how we can test key principles of planetary interiors and atmospheric formation relevant to low-mass and potentially habitable exoplanets on wider orbits.