Fig. 11.

Example of A- and E-CH₃CN lines (black histogram spectra). A non-LTE LVG model (T_k ≃ 150 K, n(H₂) ≃ 1 × 10⁶ cm⁻³, N(A-CH₃CN) = 5 × 10¹¹ cm⁻², and N(E-CH₃CN) = 6 × 10¹¹ cm⁻²) is shown overlaid in red (see Sect. 5.2).