Profile of ¹³CO (black), ATLASGAL (red), and H¹³CO⁺ (dashed blue) along the two yellow lines shown on top of the 870 μm map in the left plot. The position of the peak of Hii emission is indicated within both profiles (right) and the map (left). The left panel also gives the two main IRDC peaks. The blue asterisks indicate the position of the IRAS source (lower position) and UKIDSS source (higher position). The green contours from ATLASGAL are at 0.3 Jy, 0.4 Jy, 0.5 Jy, 0.7 Jy, 0.9 Jy, 1.3 Jy, 1.8 Jy, and 2.5 Jy.