Seminar by Paolo Sossi

Abstract

Atmospheres are not only central to the habitability of rocky planets, but they are also expressions of the nature of their interiors. Observations of exoplanets may provide answers as to the initial conditions from which rocky planets developed, and the degree to which the emergence of life of Earth is a phenomenon unique to our planet. Knowledge of the processes that lead to atmosphere formation around rocky planets, are, however, poorly known owing to extreme conditions that were likely present during the birth of rocky planets more widely. Here, we perform principal component analysis on the compositions of stars from astronomical observations, and translate this to the expected variability in the compositions of rocky planets. In detail, we show that a wide spectrum of planetary structures are expected, from reduced (O-poor) planets with Fe- and Si-bearing cores, to oxidised planets without a core at all. We use this compositional diversity, in turn, to predict the compositions of rocky outgassed atmospheres around rocky (exo)planets. We show that the compositions of atmospheres surrounding magma ocean planets can be used to infer their oxidation state.