Ratio of the truncation radius to the projected separation of the orbit as a function of eccentricity assuming the parameters of the RW Aur system and orbital inclination i = 0°. The two sets of black lines are the expectations from analytic models of tidal truncation (Eq. (9)) each one calculated for three different values of (see legend). The set of three lines at the bottom is the estimate for an object observed at apoastron, the top ones at periastron. The red dashed and blue dot-dashed lines report the measured values of R_disk,dust/a_p and R_eff,dust/a_p for RW Aur A. respectively, while the red solid and blue dotted lines are a factor of two higher, corresponding to the assumed ratio of the gas to dust radius in the disk.