An asteroseismic view of the radius valley: stripped cores, not born rocky

Understand

Various theoretical models treating the effect of stellar irradiation on planetary envelopes predict the presence of a radius valley: i.e.

• a bimodal distribution of planet radii, with super-Earths and sub-Neptune planets separated by a valley at around $\approx 2~R_\oplus$.
• Such a valley was observed recently, owing to an improvement in the precision of stellar, and therefore planetary radii.
• Here we investigate the presence, location and shape of such a valley using a small sample with highly accurate stellar parameters determined from asteroseismology, which includes 117 planets with a median uncertainty on the radius of 3.3%.