Top: overlay of the 870 μm continuum emission (black contour) on the velocity field (colors) of the C¹⁷O (3–2) line, after tapering the line emission at 1′′. The contour level of the continuum emission is the 9.0 mJy beam^-1 level (see Fig. 1). The velocity scale is shown in the color bar at the top of the panel, in km s^-1. Other symbols as in Fig. 3. Bottom: position-velocity plot along the major axis of the elongated structure (PA = − 60°), centered at the position of core B, for C¹⁷O (contours) and CH₃CN (gray scale). Vertical dotted lines mark the position of the cores identified in the continuum. The two horizontal dashed lines mark the velocities 30 km s^-1 and 32 km s^-1, associated with the hot core emission of cores B and A, respectively.