Top and middle: same as Fig. 6, but for the southern position, where the offset is centered on: α₍₂₀₀₀₎ = 12^h 24^m46^s and δ₍₂₀₀₀₎ = –71°47′20′′. It can be noted that at the location where there are no strands ( 1.5 × 10²¹ cm⁻²) that the ¹³CO emission also disappears. Bottom: ¹²CO(2–1), ¹³CO(2–1) and C¹⁸O(2–1) emission at the indicated white positions (a, b, c) in the map above with the same beam size (28′′) and spectral resolution (0.1 km s⁻¹). This indicates that in ¹²CO(2–1) there is an extra blueshifted component that is barely detected in ¹³CO(2–1). It also showsthat C¹⁸O(2–1) is not detected away from the filament crest with this data.