  Lava worlds belong to a class of short orbital period planets reaching
dayside 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 creates a tenuous, silicate-rich
atmosphere that may be confined to the permanent dayside of the planet. The
launch of JWST will provide the much needed sensitivity and spectral coverage
to characterise these worlds. In this paper, we assess the observability of
characterisable spectral features by self-consistently modelling silicate
atmospheres for all the currently confirmed targets having sufficient
substellar temperatures (> 1500 K). To achieve this we use outgassed
equilibrium chemistry and radiative transfer methods to compute
temperature-pressure profiles, atmospheric chemical compositions and emission
spectra. We explore varying melt compositions, free of highly-volatile
elements, accounting for possible atmospheric evolution. Our models include a
large number of neutral and ionic species, as well as all up-to-date opacities.
The results indicate that SiO and SiO2 infrared features are the best, unique
identifiers of silicate atmospheres, detectable using MIRI instrument of JWST.
Detection of these two species in emission would allow for strong constraints
on atmospheric thermal structure and possibly the composition of the melt. We
also propose that certain species, e.g., TiO, may be directly tied to different
classes of melts, possibly revealing surface and interior dynamics. Currently,
there are nearly a dozen confirmed lava planets ideal for characterisation of
silicate atmospheres using JWST, with two of these already accepted for the
initial General Observers program.
