Left panel: radial average profile of the ALMA continuum subtracted observation of the ¹²CO(ν= 0, J = 3−2) line (green curve) and best fit model (red curve). The shaded green area is the standard deviation of the shell over the considered ring radius. The equivalent uniform disk radius of the star is shown with a solid orange line, and the radius of the shell is represented with a dashed blue line. Right panels: radial average profile as a function of the velocity offset (left panel), best fit model (center panel), and residuals of their subtraction (right panel).