Constraints on the core mass fraction of WASP-12 b derived from the retrieved h_2f. Left: Constraints from JWST phase curve (red) and transit (blue). The black curve shows the theoretical Love number as a function of core mass fraction for a two-layer model using the formulations of Buhler et al. (2016) and Helled et al. (2014). Right: Upper limits on core mass fraction based on the precision of retrieved h_2f from different instruments. The number of phase curve and transits vists used are JWST −1 visit, HST −3 visits, PLATO −50 visits, CHEOPS −28 visits, TESS −78 visits.