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Short-period rocky exoplanets can reach surface temperatures high enough to melt their silicate crust. Theory predicts that the resulting lava oceans outgas their volatile components, attaining equilibrium with the overlying vapour. This could create atmospheres made out of silicates that mix with other volatiles that might have been present in such atmospheres. With the recently successful deployment of JWST, it is now possible to characterise these worlds.
In this talk, we assess JWST observability of key spectral features by self-consistently modelling these atmospheres. We use outgassed equilibrium chemistry and radiative transfer methods to compute temperature-pressure profiles, atmospheric chemical compositions and emission spectra. Our results indicate that SiO and SiO2 infrared features are the best in pure lava worlds. However, even a small amount of volatiles, especially H2O and H–, may hinder its observability. We also find that the C/O ratio plays a large role in determining the abundance of SiO. Detecting SiO on a strongly irradiated planet could indicate an atmosphere with high metallicity and a low C/O ratio, which may be a result of efficient interaction between the atmosphere and the underlying melt.