The eccentricity (upper row) and argument of periapsis (lower row) for the prograde disc (left column), the retrograde disc (middle column), and the test particles (right column). The argument of periapsis of the binary is constant at |$\phi _e = 0$|⁠, represented by the dot-dashed line in the lower left and middle columns. The argument of periapsis is not well defined for a circular orbit, so we only plot |$\phi _e$| for the disc and test particles when |$e>0.05$|⁠.