Evolution tracks of young substellar objects. (a) Radius tracks for objects with masses between 5 and 40 M_Jup for the first 40 Myr after formation (Phillips et al. 2020). (b) Physical parameter space of surface gravity for radii between 1 and 4 R_Jup and masses between 1 and 60 M_Jup. Tracks of different ages are overlaid. The horizontal line indicates the range of retrieved radii for TWA 27A and TWA 28 (3.06–3.11 R_Jup).