Region E₁ of the parameter space where the Laplace state P₁ is unstable to eccentricity variations. The background colour shows the normalised value of , with blue for negative values (stable) and red for positive values (unstable). The border of E₁ is highlighted with a black contour, obtained using the closed-form expression in Eqs. (21) and (22). Region E₁ is entirely contained inside the dashed brown lines, whose left and right limits r₁ and r₂ are given in Eq. (20), and whose bottom and top limits are given by Eq. (23). The Laplace state P₁ is singular atpoint S₁, in which is discontinuous.