Ring and two poles \(C_{nv}(R,\,2p)\)
In the graphs, the horizontal axis is \(\kappa_N\), the vertical is \(\kappa_S\).
\(\theta_0\) is the colatitude of the ring (so \(\theta_0=\pi/2\) lies on the equator); all are for the ring lying in the Northern hemisphere.
Lyapounov stable points in red elliptic ones in blue
The grey line in the figures for \(n\geq4\) is the instability boundary given by the higher modes.
n=2

θ0 = π/2 (= 1.57)

θ0 = 1.45

θ0 = 1.3

θ0 = 1.15

θ0 = 1.0

θ0 = 0.5