Column density and velocity structure of Musca, measured approximately along the crest of the cloud (see Fig. 1). The top panel shows the dust extinction from NIR data. The second panel shows the central velocities, V_lsr. The third and bottom panels show the nonthermal velocity dispersions, σ_NT (noncorrected) and σ_NT,corr (opacity-corrected), normalized by the sound speed c_s. The arrows in the bottom panel indicate upper limits. The red and blue points show the data for ¹³CO (2–1) and C¹⁸O (2–1), respectively. The locations of the fragments, which are closer than 100 arcsec of the cloud crest, are indicated with thin dashed lines. The thick dashed vertical lines separate the South, Center, and North regions from each other. The thick dashed horizontal line indicates the sonic velocity dispersion, and the dotted horizontal line the two times is the sonic velocity dispersion. The lower right corner of the middle panel indicates with a line a velocity gradient of 3 km s^-1. The figure is a reproduction from Hacar et al. (2016).