Evolution of the NSD model. Left: bar strength, measured by the Fourier A₂ parameter, as a function of time. The parameter A₂ was calculated considering all stars within the radius R_max that encloses 98% of the model’s mass. Right: evolution of R_max with time. The initially stable NSD starts forming a bar at t ≈ 0.5 Gyr, which reaches maximum strength at t ≈ 1.7 Gyr. Black and blue dashed lines indicate the times at which the S-NSB and W-NSB models are extracted, respectively.