Meudon PDR model results for a constant thermal pressure of P_th ~ 4.6 × 10⁷ K cm⁻³. Left panel: Meudon PDR model run with input spectral type of O5V, distance to PDR of d₀ = 0.26 pc, and far-UV flux, G₀ ~ 5.3 × 10⁴ in units of Habing field. Right panel: Meudon PDR model run with input spectral type of O 5 V, distance to PDR of d₀ = 0.12 pc, and far-UV flux, G₀ ~ 2.5 × 10⁵ in units of Habing field. The top plots shows the evolution of hydrogen species – H₂, H, and H⁺, as well as the gas temperature as a function of visual extinction A_V. The middle and bottom plots present the spatial density profiles of key PDR and dense gas tracer molecules (see main text), where each density has been normalized to its maximum value within the cloud.