Flowchart of our evolution calculations. The input parameters M_p,M_core,T_offset, 𝓡_p are the planetary mass, the core mass, the temperature offset, and the density ratio, respectively (see Sect. 3.2.4). CEPAM calculates the atmospheric helium mass fraction, the planetary radius, and the effective temperature as a function of time. If the inferred atmospheric helium mass fraction at the present time (4.56 Gyr) does not fall within the uncertainty range of the measured value by Galileo, we updated T_offset and repeated the procedure.