¹³CO (J = 2–1)/C¹⁸O (J = 2–1) line intensity ratio in six representative velocity channels. The velocity relative to the systemic velocity of v_lsr = 5.9 km s⁻¹ is listed in the top right corner of each panel and the channel width is 0.16 km s⁻¹. The line ratio is only calculated in pixels with at least a 3σ detection forboth ¹³CO and C¹⁸O. The dotted and solid contours mark the respective 3σ levels. The plotted spatial scale is such as to highlight the inner ~1′′ (140 au), that is, the disk and inner envelope. The continuum peak position is indicated with a cross and the synthesized beam is shown in the lower left corner of the lower left panel.