[Fe II] observed vs. model predicted line intensities, normalized to the 8616 Å  transition, relative to the HVC (top panel) and LVC (bottom panel). For the HVC, triangles refer to the model with a single gas component at n_e = 5 × 10⁴ cm^-3 and T_e > 15 000 K: filled (open) symbols indicate transitions with upper energies below (above) 15 000 cm^-1. Red open circles refer to the model that includes an additional high density component with n_e > 5 × 10⁶ cm^-3 to better fit the transitions at higher excitation energies.