Supercritical Hopf: fixed point becomes limit cycle as μ crosses zero
System: dx/dt = μx − y − x(x²+y²), dy/dt = x + μy − y(x²+y²)
At μ < 0: stable spiral at origin. At μ = 0: bifurcation. At μ > 0: stable limit cycle r = √μ appears.
The fixed point loses stability but a limit cycle is born — a supercritical Hopf bifurcation.