Gas and dust surface density. In blue we show the dust surface density derived from modeling the SED + near and mid-IR observations, taken from Matter et al. (2016). In red we plot the gas surface density of the best-fit model of the whole grid. In orange we show the gas surface density of the best-fit grid model restricted to only models with α_{NH inner} ≤ + 1.0. Note that the value of δ_gas depends on the gas-to-dust ratio assumed for the outer disk. This plot assumes a distance of 140 pc for HD 139614. The new Gaia distance of 131 ± 5 pc implies that the location of the gas and dust density drop is 0.4 AU closer in. However, this difference is within the uncertainties of the modeling of the data.