Left: dust temperature map (Russeil et al. 2013) derived from Herschel data observed as part of the HOBYS key program (Motte et al. 2010). This map is at the resolution of 36′′. The contours (corresponding to I = 0.4, 1.4, and 8 Jy beam⁻¹ of the BISTRO data), the crosses, and the circles are the same as in Fig. 1-top-left. The Herschel (36′′) and BISTRO (14′′) beams are shown on the left bottom of the plot as concentric filled white and black circles, respectively. Right: distribution of the ratio (see Appendix B.1 describing the derivation of the two quantities). The mean value of this distribution is 1.3, as indicated by the vertical line.