Radio and X-ray observations of double loop flares

Abstract

Interaction between an emerging loop and an overlying loop is a typical cause of flares. We call such a basic combination of loops a ‘double-loop configuration’. We reveal the topology of the two loops 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 two loops form a ‘three-legged’ structure, and the magnetic field has a ‘bipolar + remote unipolar’ structure. High-energy electrons are accelerated at the interaction region of the two loops. Thermal plasma flows like jets and surges are also originated in the interaction region.