Abstract
Magnetic null points define the topology of magnetic fields in the solar corona, Earth’s magnetosphere, and the heliosphere, and are commonly associated with magnetic reconnection. In this study, we investigate the local structure of stationary 3D resistive, incompressible magnetohydrodynamic (MHD) flows around an isolated magnetic null point and a co-located velocity stagnation point. We solve the governing equations self-consistently using a first-order local expansion of both fields about the null. We find that, for any given magnetic-null configuration, the equations admit a two-parameter family of stationary solutions whose velocity topology changes across the family. Thus, a single magnetic null can support positive-radial, negative-radial, and spiral stagnation flows. The field-aligned and spiral field-crossing solutions previously identified for constant resistivity are recovered as special cases. The associated pressure and resistivity distributions are likewise determined self-consistently and vary across the solution family, demonstrating that they are coupled to the flow topology rather than prescribed independently. The generic solutions do not require the velocity and magnetic separatrices to coincide, allowing plasma to cross the magnetic fan separatrix and providing a local reconnective flow. In this talk, I will show that, in the presence of nonuniform resistivity, the magnetic topology alone does not uniquely determine the associated stationary flow, pressure, or resistivity structure around a 3D magnetic null. I will also briefly discuss possible implications for magnetic fields in the solar corona and the apex region of the heliopause.