RGB map of [C II] (r), [O III] (g) and ¹²CO(2−1) (b) from Tarantino et al. (in preparation) and Chen et al. (in preparation), with the map of the ¹²CO(2−1) outlined in white. Contours are shown for ¹²CO(2−1) line flux levels of 5 × 10¹¹ and 5 × 10¹⁰ Wm⁻² sr⁻¹. Regions for analyses in Sect. 4 are outlined, corresponding respectively to the SFRs, N159(green), N160(red), N158(blue), an extended, less active region in [O III] (yellow) and three CO-bright filaments (brown). They are also referred to in Fig. 3, and in the plots in Figs. 5 and 6.