Energy partition in a confined flare with an extreme-ultraviolet late phase

Abstract

In this paper, we reanalyze the M1.2 confined flare with a large extreme-ultraviolet (EUV) late phase on 2011 September 9, focusing on its energy partition. The radiation ($\sim$5.4$\times$10$^{30}$ erg) in 1$-$70 {\AA} is nearly eleven times larger than the radiation in 70$-$370 {\AA}, and is nearly 180 times larger than the radiation in 1$-$8 {\AA}. The peak thermal energy of the post-flare loops is estimated to be (1.7$-$1.8)$\times$10$^{30}$ erg based on a simplified schematic cartoon. Based on previous results of Enthalpy-Based Thermal Evolution of Loops (EBTEL) simulation, the energy inputs in the main flaring loops and late-phase loops are (1.5$-$3.8)$\times$10$^{29}$ erg and 7.7$\times$10$^{29}$ erg, respectively. The nonthermal energy ((1.7$-$2.2)$\times$10$^{30}$ erg) of the flare-accelerated electrons is comparable to the peak thermal energy and is sufficient to provide the energy input of the main flaring loops and late-phase loops. The magnetic free energy (9.1$\times$10$^{31}$ erg) before flare is large enough to provide the heating requirement and radiation, indicating that the magnetic free energy is adequate to power the flare.