We performed a three-dimensional MHD simulation for reproducing emergence of a partially split flux tube into a
solar atmosphere, to investigate the following photospheric and coronal activities: merging of magnetic polarity regions (MPRs) with the same polarity and cancellation of MPRs with opposite polarities (flux cancellation) in the photosphere, which are associated with generation of a multiple flux-domain system in the corona. By analyzing the simulated data, we demonstrated how a satellite MPR with a rotational flow in it merged into a main MPR with an opposite rotational flow in it, generating a new rotational flow in the same direction as that observed in the satellite MPR. In accordance
with the merging process, flux cancellation via U-loop emergence also proceeded in the photosphere. In the corona a current layer separating different flux domains propagated outward as these domains expanded. We also examined injection of magnetic
flux, magnetic energy, and relative magnetic helicity into the atmosphere by the partially split flux tube, presenting a physical explanation of the temporal development of mutual magnetic helicity in the multiple flux-domain system.
Reference
Magara, T.
2008 PASJ, 60, 809
