![Integrated intensity ratio map $\int _{4}^{9}T_{\rm MB}^{12}(\upsilon ){d}{\it \upsilon } / \int _{4}^{9} T_{\rm MB}^{13}({\it \upsilon } ){d}{\it \upsilon }$ (left) and $\int _{4}^{9}T_{\rm MB}^{13}(\upsilon ){d}{\it \upsilon } / \int _{4}^{9} T_{\rm MB}^{18}({\it \upsilon } )d{\it \upsilon }$ (right). The $T_{\rm MB}^{12}$, $T_{\rm MB}^{13}$, and $T_{\rm MB}^{18}$ correspond to the mean beam brightness temperature of the 12CO(1–0), 13CO(1–0), and C18O(1–0) emissions, respectively, $\upsilon$ is the line-of-sight velocity in the range [4–9] km s−1. The integrated intensity maps are the same as in figure 2. For the right-hand side map, only pixels with $T_{\rm MB}^{18}>5\, \sigma$ have been considered, where σ = 0.2 K (section 2). The 12CO(1–0) emission is optically thick over the entire observed field. The C18O(1–0) and 13CO(1–0) emissions are optically thin. (Color online)](https://oup.silverchair-cdn.com/oup/backfile/Content_public/Journal/pasj/70/5/10.1093_pasj_psy095/3/pasj_70_5_96_f11.jpeg?Expires=1750037684&Signature=SQFTw2~rQf700J3NimFw9VQ4m7aBojU6l1XJQmNR~bV76107c36ZfVa0JKOSUSJykiobe692sdvqDhkq2zFfsvh~mVU0kAuqeGtSCHj~lKYCKfW7kXQcTQq0WkAFK-BA3cJCLNLsRQz-Gp1p5dRjXv5eQV-t7~FY4gvm1b5ZlWPQRj6tKiy6Qjs0lwuMat6LERMSOnBdU3XbcVQ1GI~xAFIiT6St-aLSkoHvfYeHo2IIxVNt10DKwOrgU6NtFj~pTECUUG47Z~cndQKbrV1zL2sPoXPwXIZFtjYUe659L1QhYLZUp~e4dY-~pCfxuIBFWNuDQ5U7UmFKcrRcBQ4g~w__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Integrated intensity ratio map |$\int _{4}^{9}T_{\rm MB}^{12}(\upsilon ){d}{\it \upsilon } / \int _{4}^{9} T_{\rm MB}^{13}({\it \upsilon } ){d}{\it \upsilon }$| (left) and |$\int _{4}^{9}T_{\rm MB}^{13}(\upsilon ){d}{\it \upsilon } / \int _{4}^{9} T_{\rm MB}^{18}({\it \upsilon } )d{\it \upsilon }$| (right). The |$T_{\rm MB}^{12}$|, |$T_{\rm MB}^{13}$|, and |$T_{\rm MB}^{18}$| correspond to the mean beam brightness temperature of the 12CO(1–0), 13CO(1–0), and C18O(1–0) emissions, respectively, |$\upsilon$| is the line-of-sight velocity in the range [4–9] km s−1. The integrated intensity maps are the same as in figure 2. For the right-hand side map, only pixels with |$T_{\rm MB}^{18}>5\, \sigma$| have been considered, where σ = 0.2 K (section 2). The 12CO(1–0) emission is optically thick over the entire observed field. The C18O(1–0) and 13CO(1–0) emissions are optically thin. (Color online)
