Top row: observational maps of the velocity-integrated brightness temperatures, T_b, of the Hi 21 cm (left), ¹²CO 2.6 mm (middle), and ¹³CO 2.7 mm (right) emission lines toward the G139 region; these maps are from Winkel et al. (2016), Yuan et al. (2021), and Yuan et al. (2022), respectively. Second row: maps of the velocity-integrated opacity-corrected brightness temperatures, T_b⋆, of the Hi (left) and ¹²CO (right) lines, where $T_{\text{b}*}^{12\text{CO}}$ is derived based on the combined ¹²CO and ¹³CO data. Third row: same maps resampled to the common 26×26 pixel grid (pixel size = 4’). Fourth row: reconstructed maps after application of the Gaussian decomposition algorithm ROHSA. Bottom row: maps of the residuals obtained by subtracting the reconstructed ROHSA maps from the resampled input maps. The color bars for Hi and CO (superscript 12 dropped) can be rescaled to dust intensity at 353 GHz using the best-fit values of the conversion factors derived in Sect. 3.2 (see Fig. 3). The resulting ranges in the third and fourth rows are ≃[0, 3.5 MJy sr⁻¹] for Hi and ≃[0, 2.5 MJy sr⁻¹] for CO.