On the 2012 October 23 circular ribbon flare: emission features and magnetic topology

Abstract

Circular ribbon flares are usually related to spine-fan type magnetic topology containing null-points. In this paper, we investigate an X-class circular ribbon flare on 2012 October 23, using the multi-wavelength data from the \textit{Solar Dynamics Observatory}, \textit{Hinode}, and the \textit{Ramaty High Energy Solar Spectroscopic Imager}. In \ion{Ca}{2} H emission, the flare showed three ribbons with two highly elongated ones inside and outside a quasi-circular one, respectively. A hot channel was displayed in the extreme ultraviolet (EUV) emissions that infers the existence of a magnetic flux rope. Two hard X-ray (HXR) sources in the 12--25 keV energy band were located at the footpoints of this hot channel. Using a nonlinear force-free magnetic field extrapolation, we identify three topological structures: (1) a 3D null-point, (2) a flux rope below the fan of the null-point, and (3) a large-scale quasi-separatrix layers (QSL) induced by the quadrupolar-like magnetic field of the active region. We find that the null-point is embedded within the large-scale QSL. In our case, all three identified topological structures must be considered to explain all the emission features associated with the observed flare. Besides, the HXR sources are regarded as the consequence of the reconnection within or near the border of the flux rope.

30 pages, 8 figures

References in corpus (15)

• The Solar Optical Telescope for the Hinode Mission: An Overview
• Torus instability
• Optimization code with weighting function for the reconstruction of coronal magnetic fields
• Preprocessing of vector magnetograph data for a non-linear force-free magnetic field reconstruction
• Non-linear force-free field modeling of a solar active region around the time of a major flare and coronal mass ejection
• Jets in coronal holes: Hinode observations and 3D computer modelling
• Sigmoid-to-Flux-Rope Transition Leading to A Loop-Like Coronal Mass Ejection
• Formation of a Double-decker Magnetic Flux Rope in the Sigmoidal Solar Active Region 11520
• Current amplification and magnetic reconnection at a 3D null point. I - Physical characteristics
• Simulating the in situ condensation process of solar prominences
• On the Relationship Between a Hot-channel-like Solar Magnetic Flux Rope and its embedded Prominence
• On the origin of the Extreme-Ultraviolet late phase of solar flares
• The magnetic field topology associated to two M flares
• Magnetic Flux Change and Cancellation Associated with X-class and M-class Flares
• Current sheets at three-dimensional magnetic nulls: Effect of compressibility

Cited by in corpus (5)

• A Circular White-Light Flare with Impulsive and Gradual White-Light Kernels
• Slipping Magnetic Reconnection of Flux Rope Structures as a Precursor to an Eruptive X-class Solar Flare
• Generation mechanisms of quasi-parallel and quasi-circular flare ribbons in a confined flare
• Observation of a 3D magnetic null point
• The 17 February 2013 sunquake in the context of the active region's magnetic field configuration