Collapse of the null point visualised with field lines in the isotropic case. Field lines are plotted from a circle of radius 0.05 around the upper and lower spine footpoints. Contours of |j| = 60 are also plotted and reveal the strong current within the spine as well as the formation of the central sheet associated with the spine-fan reconnection. At t = 18.5 the bulk of the field lines making up the core of the spine have reconnected.