Evolution of a test particle that experiences the secular resonance 2𝑔 − s = s₈. The initial orbital elements are a = 47.55 au, e = 0.2, i = 19°, Ω = Ω₈, ω = 358.86°, and M = M₈. From top to bottom, the panels show the semi-major axis, eccentricity, inclination, critical angles of the 1:2 eccentricity-type resonance, of the 2:4 inclination-type resonance, and of the 2𝑔 − s = s₈ secular resonance. The solid lines indicate the position of 180°.