Spectra of the opacity-corrected brightness temperatures, $T_{\text{b}*}^{\text{HI}}$ and $T_{\text{b}*}^{\text{CO}}$, averaged over the 26×26 pixels of the common (l, b) grid, toward the G139 region. The observed spectra are plotted in black dashed line, the reconstructed spectra obtained after application of the Gaussian decomposition algorithm ROHSA are plotted in black solid line, and the spectra of the individual Gaussian kinematic components, which are ordered (for each tracer) by increasing mean velocity, are plotted in color. The $T_{\text{b}*}^{\text{HI}}$ and $T_{\text{b}*}^{\text{CO}}$ spectra can be rescaled to dust intensity per unit velocity at 353 GHz using the best-fit values of the conversion factors derived in Sect. 3.2 (see Fig. 3).