Vivien Parmentier (Oxford University, @V_Parmentier) has produced an explanatory Twitter thread on his latest paper with Jonathan Fortney (@jjfplanet). Since this concerns WASP exoplanets, let’s reproduce it here:

[The symbols include data points for WASP-43b, WASP-14b, WASP-19b, WASP-18b and WASP-103b, along with other hot Jupiters.]