Longitude–velocity (LV) diagrams of the HI emission (from THOR, left panel) and ¹³CO emission (from GRS, right panel) toward the region presented in Fig. 7. In the HI LV diagram, the shadow around 0 ≤ v_LSR ≤ 45 km s⁻¹ and the vertical line around 0 ≤ v_LSR ≤ 75 km s⁻¹ correspond to absorption toward the supernova remnant (SNR) G34.7-0.4 (W44) and the HII region G34.256+0.146, respectively.