Main velocity component observed over the G010.32−00.15 field. Left: velocity field obtained with the HCO⁺ (1−0) molecular line. The contours are for the column density (levels of 0.5, 0.75, 1, 1.5, and 2 × 10²³ cm^-2). The 38″ beam is at the lower left. Right: velocity profile from a region of 36″ × 36″ centred on C3, at . The HCO⁺ line shows self-absorption whereas the H¹³CO⁺ line is optically thin. The red dotted line shows the velocity obtained by fitting the splitted HCO⁺ line with one gaussian.