2018ApJ...868..113T

We present an improved method to measure the rotation curves for disks with nonaxisymmetric brightness profiles initially published in Teague et al. Application of this method to the well studied AS 209 system shows substantial deviations from Keplerian rotation of up to ±5%. These deviations are most likely due to perturbations in the gas pressure profile, including a perturbation located at ≃250 au and spanning up to ≃50 au that is only detected kinematically. Modeling the required temperature and density profiles required to recover the observed rotation curve, we demonstrate that the rings observed in micrometer scattered light are coincident with the pressure maxima, and are radially offset from the rings observed in millimeter continuum emission. This suggests that if rings in the NIR are due to submicrometer grains trapped in pressure maxima, then there is a vertical dependence on the radius of the pressure minima.