sub-Neptunes are like Karakara senbei, observing their interiors is challenging!

A study reveals how interiors of exoplanets can be infered from observation of their atmospheres.

With recent advances in astronomical observation techniques, exoplanetary atmospheres can now be characterized with increasingly high precision, opening new opportunities to infer information about planetary interiors from observable atmospheric properties. This is particularly important for sub-Neptunes, planets with radii a few times that of Earth, whose interiors remain uncertain as to whether they are predominantly rocky or icy. We have developed MELTYQ, an analysis framework that constrains the state of rocky magma in a planet’s interior while directly incorporating observational noise in atmospheric spectra.

Applying MELTYQ to data obtained with JWST, we show that a hypothesized rocky magma interior can reproduce the observed spectrum. This study represents a first step toward uncovering the unknown interiors of exoplanets, which are otherwise extremely difficult to observe directly, a challenge akin to guessing the toy hidden inside a French "Galette des Rois" or Japanese "Karakara senbei"... without ever taking a bite.

Read the full paper: Link