Velocity dispersion inside the protostar computed in radial bins (panel a) and average specific entropy (panel b), for simulations with a maximum refinement level of 25 (Δx = 2.93 × 10⁻⁴AU, blue curves), 26 (Δx = 1.46 × 10⁻⁴AU, orange curves), and 27 (Δx = 7.34 × 10⁻⁵AU, green curves). These are shown at a moment in time where all three protostars have reached similar masses (5.9 × 10⁻³ M_⊙ for ℓ_max = 25, 5.75 × 10⁻³ M_⊙ for ℓ_max = 26 and ℓ_max = 27).