Mass-density diagram of the currently known transiting exoplanets with precisely measured mass and radius. The grey points denote values taken from TEPCat. Their error bars have been suppressed for clarity. The position of WASP-174bis shown in green with error bars. Four planetary models, with various heavy-element core masses (10, 25, 50, and 100 Earth mass) and another without a core are plotted for comparison. They were estimated for a planet at 0.045 au from a parent star with an age of 3.16 Gyr (Fortney et al. 2007).