Activity Caused by Interacting Loops and Evolution of Magnetic Field

Abstract

Interaction between newly emerging flux regions and overlying loops is a well-known cause of various types of activity - flares, jets, and surges. We studied magnetic configuration which consists of an emerging loop and an overlying loop, and the relation between the evolution of emerging flux regions and various active phenomena. The main conclusions are as follows.(1) We reveal the topology of an emerging loop and an overlying loop using microwave and soft X-ray observations of the flares, along with their magnetograms. Two of the footpoints of the loops, one from the emerging loop and the other from the overlying loop, are included in a single magnetic polarity patch. Therefore, the footpoints of the two loops do not form a quadrapole structure, but they are distributed in three magnetic patches. The two loops form a ‘three-legged’ structure, and the magnetic field has a ‘bipolar + remote unipolar’ structure.(2) Emergence of parasitic polarities near the main preceding-polarity region or the following-polarity region in active regions are observed. The life-time of the parasitic polarities are a few days. Not only flares, but microflares, jets, and surges occur at the parasitic polarities, and they repeat homologously during the evolution of the parasitic polarities. Consequently, emerging flux activity produces a double-loop configuration with an overlying loop, and this magnetic configuration is a source of various active phenomena.