Properties observed toward the clump-hub (black dashed ellipse in Fig. 19). Top: PF as a function of I for SNR(I) > 25 and SNR(PI) > 3. The vertical small black lines show the statistical uncertainties on PF. The black, purple, and cyan lines indicate the best linear fits to the upper 95% percentiles of the distribution, the data points with , and the datapoints with , respectively.The best fit slopes are indicated on the plot. For comparision, the yellow and red lines indicate slopes of − 0.5 and − 1, respectively. Bottom: variation of PF (solid lines) and I (dashed lines) for two horizontal cuts from east to west, crossing the star forming regions I and I(N) in red and blue, respectively. The peak in I of the blue dashed profile at ~1.6 pc corresponds to the position of the ridge (crest 4).