a) C¹⁸O intensity map (white contours) overlaid on the ¹³CO line image. Both lines have been integrated over the velocity range between 22 and 29 km s^-1. Contours start from 1.2 K km s^-1(3σ) to 3.6 K km s^-1(9σ) by 0.8 K km s^-1(2σ). The horizontal bar represents 15 pc at the distance of 2.42 kpc. The purple solid line marks the highest H₂ column density line of the filament S287-main along its long axis. b) Zoom in the region indicated in Fig. 10a. Contours start from 1.2 K km s^-1(3σ) to 3.6 K km s^-1(9σ) by 0.6 K km s^-1(1.5σ). The clumps are marked with red crosses and ellipses, and their corresponding names are also given. The RMS MYSOs are marked with blue circles. The C¹⁸O beam width is shown in the lower right corner of the panel. c) Same as Fig. 10b. d) Same as Fig. 10b.