Results from the radiative modelling of the¹² CO (J = 2−1) and ¹²CO (J = 1−0) transitions with RADEX. The ratio between the ¹²CO (J = 2−1) and ¹²CO (J = 1−0) line peaks ratio is plotted as a function of kinetic temperature (T_kin) for different values of H₂ density (dens, in cm⁻³) and column density (cdmol, in cm⁻²). A horizontal line for ratio equals to 2 indicates the conditions of the molecular gas in the regions A, B, and D around VRO 42.05.01.