2D 1σ confidence regions of HD 207897 b for the mass estimation with activity period on 37.6 d (blue) and with activity period on 35.9 d (red). Solid lines indicate the confidence intervals of scenario 1, and dashed lines correspond to scenario 2, in which the stellar abundances are also included as input data in the MCMC interior structure analysis. The MMF is defined as MMF = 1 - CMF - WMF. The green dot and brown square indicate the position of Earth and Mercury in the ternary diagram, respectively.