Speaker
Description
The formation of the first solids in protoplanetary disks sets the chemical foundations of planetary systems, yet their origin remains poorly understood. Classical models assume equilibrium condensation in a cooling gas, but increasing observational and cosmochemical evidence suggests that this assumption is not valid in dynamically evolving disks. Infrared observations (Spitzer, JWST) reveal strong spatial and temporal variability in dust mineralogy, while meteorites record discrete redox states and mineral assemblages that are difficult to reconcile with equilibrium chemistry alone.
Here, I present my recent work with an innovative method, in which I compute time-dependent gas–solid reactions along realistic pressure–temperature–time (P–T–t) trajectories. Our results show that mineralogy and oxidation state are primarily controlled by cooling rate and pressure, rather than by bulk composition. Remarkably, this approach naturally reproduces the three main classes of chondritic materials (enstatite, ordinary, and carbonaceous) and their redox diversity, without invoking large-scale chemical gradients.
A key implication is that protoplanetary disks behave as time-dependent thermochemical reactors. In this context, processes such as accretion bursts, vertical transport, and disk winds drive rapid heating and cooling cycles, leading to kinetically controlled condensation pathways. This framework also predicts the formation of Fe-rich and hydrated minerals directly during condensation, opening new perspectives on the origin of water in terrestrial planets and challenging the classical concept of the snowline.
These results suggest a paradigm shift in which planetary materials record their thermodynamic history rather than their formation location. This work provides a unified framework to connect disk observations, meteoritic records, and exoplanet compositions, and opens new directions for understanding the chemical diversity of planetary systems.