Separators in 3D quiet-sun magnetic fields

At the confluence of four regions of different magnetic connectivity lies a distinct topological candidate for coronal heating, namely the magnetic separator. In this study, a method for tracing separator curves is developed and the statistical properties of separators in coronal fields are subsequently explored by analysing a model field with an exponential source distribution, similar to that studied by Schrijver and Title ( 2002). Magnetic fields based on data from an observed sequence of MDI magnetograms are also considered as a case study. The picture that emerges is one in which there are many more magnetic separators than previously thought, since many separators arise from each null point. For an exponential source distribution, an average of 10.1 +/- 0.13 separators per null are found, of which 1.04 +/- 0.04 "multiply link" pairs of nulls (i.e., there is more than one separator linking such pairs of nulls). For the observed sequence of magnetograms, these figures are 7.63 +/- 0.2 and 0.99 +/- 0.059, respectively. The results obtained here show that separators have a tendency to group together into trunks about a null. In the case of prone nulls, these trunks lie either normal to the photospheric surface or on it. It is also established that pairs of coronal nulls are frequently interconnected, suggesting that they may have been created by purely coronal bifurcations.