Channel maps of the ²⁸SiO v = 0 J = 5–4 line emission. The contours in each channel are 3, 6, 9, 12, 15, 18, 21, 24, 27, 30 and 33 times the rms noise in the peak line channel (0.27 Jy beam^-1). Every channel is 2.5 km s^-1 wide and the central LSR velocity is indicated in the lower right corner of each box. The bulk of the emission comes from an extended structure elongated northeast-southwest and centered at Source I (white star in each channel). The ALMA synthesized beam is indicated as a white ellipse in the lower left panel.