Fig. 5

Torus canards in the HR system (Equations 4a-4c) at $s=-1.95$: (a) torus canard without head at $b_1=-0.16046985$, and (b) torus canard with head at $b_1=-0.16047$. In each frame, the upper panel shows the time series of the x variable (previously included in Figure 3), and the lower panel shows the Poincaré map of the torus canard trajectory in phase space. The bifurcation diagrams of the fast system include branches of fixed points and periodic orbits, and follow the plotting conventions in Figure 2.