Maps of the CN emission averaged over the frequency interval of the main component. The unit of the colour bar is Jy beam⁻¹. The blue contours show the continuum emission at 1.3 mm with levels of 0.005, 0.010, and 0.020 Jy beam⁻¹, and the names of the millimetre source used in Table 2 are indicated in each case. The 1σ rms noise level is about 0.0015 Jy beam⁻¹ for both the continuum and the averaged line emission. The horizontal lines at the bottom left corner in each panel represent a size of 0.05 pc for each case.