Determination of the Topology Skeleton of Magnetic Fields in a Solar Active Region

The connectivity of the coronal magnetic field establishes discrete domains, defined by a "skeleton" consisting of magnetic nulls, spines and fans, separatrices, and separators - that is, unless the plasma physics becomes interesting. In comparing static cases we talk about magnetic reconnection to relink the domains, and incidentally a flare or CME may have happened during that relinking. This paper describes a partition of the coronal field of a particular solar active region, NOAA 10720, into no less than six 3D nulls (including a "spiral null") plus associated paraphernalia. We never know if these skeletons are complete, though, because the observations have limited spatial resolution. Note the lovely twist in the field, which the authors refer to as a "magnetic wreath."