Mass-period (top panel) and mass-radius (bottom panel) diagrams for well-characterised planets with masses and radii measured with a precision better than 30%, from 1 M_⊕ up to 1.5 M_J and 1 R_⊕ up to 1.5 R_J, from the TEPCat database (February 2022; Southworth 2011) and http://exoplanet.eu. HD 191939 planets are colour coded and marked with a filled circle with error bars (the radii of HD 191939 e and g are forecasted). Vertical colour bands indicate the ±1σ mass regions of HD 191939 g and e. Temperate planets with T_eq = 250–395 K are marked by blue squares. The mass-radius panel also shows theoretical composition models at 300 K from Zeng et al. (2019).