Simulated mass loss rate Ṁ for an artificial planet with M_p = 1.3 × 10³⁰ g and R_p = 10¹⁰ cm, subject to different levels of stellar XUV irradiation (panel a) and simulated mass outflow rates for eight planets subject to different levels of stellar XUV irradiation, for a total of 81 simulations (panel b). In panel a, the dashed red line represents the results of the simulations carried out by Murray-Clay et al. (2009), under the assumption of a pure hydrogen atmosphere and mono-energetic irradiation field at 20 eV. The blue line represents the results obtained by ATES under the same assumptions. The green line represents the ATES results for a pure hydrogen atmosphere subject to a power-law irradiation spectrum with slope v⁻¹. The black line refers to a primordial hydrogen-helium atmosphere with a power-law spectrum, that is, the standard setup for ATES. The adopted color scheme in panel b is the same as shown in Figs. 1a, b and 2. In both panels, the dotted lines represent linear proportionality between mass loss rate and flux.