SOLARNET Conference: The Many Scales of the Magnetic Sun

Solar events such as flares and coronal mass ejections are the most energetic phenomena affecting interplanetary space in timescales ranging from minutes to a few days. There has been, in recent years, a strong interest in characterizing the processes that inject magnetic energy and helicity in solar active regions (ARs) and the mechanisms that destabilize their magnetic structure leading to the energy released during those events. We analyze the magnetic evolution of AR NOAA 11476 that produced a series of minifilament confined eruptions of the “surge” type accompanied by M-class flares. In a previous work, we found that these events are associated to the presence of a small rotating bipole that emerged in the middle of the globally bipolar AR magnetic configuration. The bipole rotation preceded and concurred in time with the observed ejections. Magnetic flux cancellation is also identified along the polarity inversion line of the bipole where the minifilaments were recurrently formed and ejected. Here we combine the analysis, for the full AR and the rotating bipole, of the evolution of a series of magnetic parameters computed from SDO/HMI vector magnetograms with estimations of the magnetic energy and magnetic helicity injection obtained using the Differential Affine Velocity Estimator for Vector Magnetograms (DAVE4VM) method. This procedure is based on the determination, from vector magnetograms, of the affine velocity field constrained by the induction equation. Our results provide a series of relations between the studied parameters that define proxies of the magnetic evolution of the AR that, eventually, can be used as possible precursors of active events.