This work employs Hall magnetohydrodynamic (MHD) simulations to study the
X-lines formed during the reconnection of magnetic fields with differing
strengths and orientations embedded in plasmas of differing densities. Although
random initial perturbations trigger the growth of X-lines with many
orientations, at late time a few robust X-lines sharing an orientation
reasonably consistent with the direction that maximizes the outflow speed, as
predicted by Swisdak and Drake [Geophys. Res. Lett., 34, L11106, (2007)],
dominate the system. The existence of reconnection in the geometry examined
here contradicts the suggestion of Sonnerup [J. Geophys. Res., 79, 1546 (1974)]
that reconnection occurs in a plane normal to the equilibrium current. At late
time the growth of the X-lines stagnates, leaving them shorter than the
simulation domain.Comment: Accepted by Physics of Plasma
