Radius with the highest mean gas density (r_ρmax) as a function of time, t for the embedded star simulations. Different colours correspond to different resolutions resulting from different SPH particle masses (M_SPH). Top panel: r_ρmax for all simulations as a function of t. Lines with open circles correspond to simulations where the gas density, ρ_gas = 10 M_⊙ pc⁻³ and lines with filled circles to simulations with a gas density, ρ_gas = 100 M_⊙ pc⁻³. Bottom panel: simulations with ρ_gas = 100 M_⊙ pc⁻³ and subtract Ṁ/M_SPH (the time of the first SPH particle creation) from t. The black solid line shows the analytical solution for the shell radius of an energy driven flow in a constant density medium (Dyson 1984).