Observational Investigation of Energy Release in the Lower Solar Atmosphere of a Solar Flare

TL;DR

This study combines high-resolution optical and magnetic observations to investigate the energy release mechanisms in the lower solar atmosphere during a solar flare, highlighting magnetic reconnection near the polarity inversion line.

Contribution

It provides new insights into the magnetic topology and reconnection processes in the lower solar atmosphere during a flare using combined observational and modeling techniques.

Findings

Magnetic flux tubes interact at the polarity inversion line.

Energy release occurs in the dense chromosphere near the PIL.

Magnetic reconnection is triggered by flux tube interaction.

Abstract

We study flare processes in the lower solar atmosphere using observational data for a M1-class flare of June 12, 2014, obtained by New Solar Telescope (NST/BBSO) and Helioseismic Magnetic Imager (HMI/SDO). The main goal is to understand triggers and manifestations of the flare energy release in the lower layers of the solar atmosphere (the photosphere and chromosphere) using high-resolution optical observations and magnetic field measurements. We analyze optical images, HMI Dopplergrams and vector magnetograms, and use Non-Linear Force-Free Field (NLFFF) extrapolations for reconstruction of the magnetic topology. The NLFFF modelling reveals interaction of oppositely directed magnetic flux-tubes in the PIL. These two interacting magnetic flux tubes are observed as a compact sheared arcade along the PIL in the high-resolution broad-band continuum images from NST. In the vicinity of the PIL, the NST H alpha observations reveal formation of a thin three-ribbon structure corresponding to the small-scale photospheric magnetic arcade. Presented observational results evidence in favor of location of the primary energy release site in the dense chromosphere where plasma is partially ionized in the region of strong electric currents concentrated near the polarity inversion line. Magnetic reconnection may be triggered by two interacting magnetic flux tubes with forming current sheet elongated along the PIL.