Point vortices exhibit asymmetric equilibria

The equilibrium patterns formed by interacting vortices have been puzzled over in a variety of contexts since Kelvin's theory of vortex atoms1 was debunked by quantum mechanics. These patterns have, for example, appeared in atmospheric and oceanographic flows2,3 and in rotating superfluid helium4,5. For a particular mathematical model, the point vortex equations, a catalogue of equilibria was drawn up some twenty years ago6. We have revisited the point vortex model by a different approach and have discovered a host of new equilibrium states, including asymmetric patterns devoid of rotational or reflectional symmetry.