Deprojected and azimuthally-averaged radial profiles of the continuum emission, and CO, HCO⁺, H¹³CO⁺, HC¹⁵N line emission ratio (from top to bottom, then left to right). The coloured shaded region on each profile represents the errors (see text for details). The vertical dashed grey lines highlight the rings and gaps in the mm-dust continuum profile and the dashed grey profile is the best-fit model of the continuum uv data from (Walsh et al. 2016) and is normalised to the peak value in each plot. The dotted black line on the HC¹⁵N plot is the continuum model convolved with a 50 au beam from Walsh et al. (2016) and is normalised to the peak value in each plot.