The Exceptional Aspects of the Confined X-class Flares of Solar Active Region 2192

TL;DR

This study analyzes the unusual confinement of X-class solar flares in active region NOAA 2192, revealing magnetic field configurations that prevent eruptions and evidence of multiple reconnection processes with high-energy electron acceleration.

Contribution

It provides new insights into the magnetic conditions causing confined flares and documents multiple reconnection events within single flares, which is a novel observation.

Findings

Strong surrounding magnetic fields confine major flares.

Multiple magnetic reconnection processes occur within single flares.

Electrons are accelerated to unusually high energies during these events.

Abstract

During late October 2014, active region NOAA 2192 caused an unusual high level of solar activity, within an otherwise weak solar cycle. While crossing the solar disk, during a period of 11 days, it was the source of 114 flares of GOES class C1.0 and larger, including 29 M- and 6 X-flares. Surprisingly, none of the major flares (GOES class M5.0 and larger) was accompanied by a coronal mass ejection, contrary to statistical tendencies found in the past. From modeling the coronal magnetic field of NOAA 2192 and its surrounding, we suspect that the cause of the confined character of the flares is the strong surrounding and overlying large-scale magnetic field. Furthermore, we find evidence for multiple magnetic reconnection processes within a single flare, during which electrons were accelerated to unusual high energies.