Energy Partition in Two M-class Circular-ribbon Flares

Abstract

In this paper, we investigate the energy partition of two homologous M1.1 circular-ribbon flares (CRFs) in active region (AR) 12434. They were observed by SDO , GOES , and RHESSI on 2015 October 15 and 16, respectively. The peak thermal energy, nonthermal energy of flare-accelerated electrons, total radiative loss of hot plasma, and radiant energies in 1–8 Å and 1–70 Å of the flares are calculated. The two flares have similar energetics. The peak thermal energies are (1.94 ± 0.13) × 10 30 erg. The nonthermal energies in flare-accelerated electrons are (3.9 ± 0.7) × 10 30 erg. The radiative outputs of the flare loops in 1–70 Å, which are ∼200 times greater than the outputs in 1–8 Å, account for ∼62.5% of the peak thermal energies. The radiative losses of SXR-emitting plasma are one order of magnitude lower than the peak thermal energies. Therefore, the total heating requirements of flare loops including radiative loss are (2.1 ± 0.1) × 10 30 erg, which could sufficiently be supplied by nonthermal electrons.