Mass-radius diagram for TOI-283 b (red star) and known transiting planets with mass determinations with a precision better than 30% (parameters taken from the TEPCat database; Southworth 2011). Planets orbiting K-type stars (4000 ≤ T_eff ≤ 5300 K) are marked with orange circles. The lines in the mass-radius diagram represent the composition models of Zeng et al. (2016, 2019) for planets with pure iron cores (100% Fe, brown line), Earth-like rocky compositions (32.5% Fe plus 67.5% MgSiO₃, dashed green line), Earth-like compositions with a 0.1% H₂ envelope (dotted purple line), and a water world with a 0.1% H₂ gas envelope (dash-dotted blue line). We show some Solar System planets for reference (Venus, Earth, Uranus, and Neptune).