ner_tags: O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject I-CelestialObject O B-CelestialObject O O O O B-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObject B-CelestialObject O B-CelestialObject O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
tokens: order of Type 2, 3, and 4 successively. The Type 1 clumps are puzzling, because we would expect that they are the clumps just before the onset of cluster formation in a stage prior to the Type 2 clumps, but their chemical compositions indicate that they are older than the Type 2 clumps. We will discuss the nature and origin of the Type 1 clumps in Section 4.3 . 4.2. Velocity Structures of the Clumps The results shown in Figures 11 – 12 suggest that there are interesting systematic differences among the types of clumps. In the following, we further investigate the velocity structures of the Types 1–3 clumps. Figure 15 shows the distribution of the velocity dispersion σ obs measured with the 13 CO and C 18 O emission lines for the 24 clumps as a function of the projected distance from the cluster center (for Type 2 and Type 3 clumps) or from the clump peak (for Type 1 clumps). Values of σ obs measured with the two emission lines are shown by dots with different colors—gray and pink for the 13 CO and C 18 O emission lines. We found that σ obs at the center of the clumps differs depending on the types of the clumps; the σ obs values of Type 1 (except for clumps 3890a and 3890b), Type 2 (except for 4417b), and Type 3 are mostly ≲0.5 km s −1 , ≳1.0 km s −1 , and ≳0.5 km s −1 , respectively. This suggests that the large velocity dispersion at the clump center is a typical feature of cluster-forming Type 2 and Type 3 clumps. The velocity dispersion is particularly large in the Type 2 clumps, indicating that there must be a lot of motions around the clump center in the beginning of cluster formation. Figure 15. Variation of velocity dispersion ( σ obs ) for each clump as a function of the distance from the cluster center (for the Types 2 and 3 clumps) or the C 18 O emission peak position (for the Type 1 clumps). The different color dots represent the velocity dispersion values measured from the 13 CO (gray) and C 18 O (pink) data. Blue and red squares represent the median values of σ obs in the 0.2 pc bin for the 13 CO and the C 18 O data, respectively. The error bars show the standard deviation of each piece of data in the bins. We also investigated the C 18 O distributions based on the position–velocity (PV) diagrams for all of the clumps. In Figure 16 , we show examples of the PV diagrams measured along the major and minor axes of the clumps, which are displayed in panels (b) and (c) of the figure. As denoted by the white broken circles in panels (b), we found that the PV diagrams of some Type 2 clumps measured along the major axis show double peaks separated by ∼1 km s −1 , and they are symmetrically located with respect to the clump centers. This feature is seen only in three of the seven Type 2 clumps (4417c, 4423a, and 4753b), but not in Type 1 or Type 3 clumps. Figure 16. Distributions of the H 2 column density derived from the C 18 O integrated intensity, observed position–velocity diagram measured along the major axis (cut 1–1′) , and that