Transition from circular-ribbon to parallel-ribbon flares associated with a bifurcated magnetic flux rope

Abstract

Magnetic flux ropes play a key role in triggering solar flares in the solar atmosphere. In this paper, we investigate the evolution of active region NOAA 12268 within 36 hours from 2015 January 29 to 30, during which a flux rope was formed and three M-class and three C-class flares were triggered without coronal mass ejections. During the evolution of the active region, the flare emission seen in the H$\alpha$ and ultraviolet wavebands changed from a circular shape (plus an adjacent conjugated ribbon and a remote ribbon) to three relatively straight and parallel ribbons. Based on a series of reconstructed nonlinear force-free fields, we find sheared or twisted magnetic field lines and a large-scale quasi-separatrix layer (QSL) associated with 3D null points in a quadrupolar magnetic field. These features always existed and constantly evolved during the two days. The twist of the flux rope was gradually accumulated that eventually led to its instability. Around the flux rope, there were some topological structures, including a bald patch, a hyperbolic flux tube and a torus QSL. We discuss how the particular magnetic structure and its evolution produce the flare emission. In particular, the bifurcation of the flux rope can explain the transition of the flares from circular to parallel ribbons. We propose a two-stage evolution of the magnetic structure and its associated flares. In the first stage, sheared arcades under the dome-like large-scale QSL were gradually transformed into a flux rope through magnetic reconnection, which produced the circular ribbon flare. In the second stage, the flux rope bifurcated to form the three relatively straight and parallel flare ribbons.

arXiv comment31 pages, 9 figures, 2 tables; Accepted for publication in ApJ

References in corpus (39)

• A Model for Solar Coronal Mass Ejections
• Confined and ejective eruptions of kink-unstable flux ropes
• The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance
• Preprocessing of vector magnetograph data for a non-linear force-free magnetic field reconstruction
• A Critical Assessment of Nonlinear Force-Free Field Modeling of the Solar Corona for Active Region 10953
• VFISV: Very Fast Inversion of the Stokes Vector for the Helioseismic and Magnetic Imager
• Observation of An Evolving Magnetic Flux Rope Prior To and During A Solar Eruption
• Non-linear force-free field modeling of a solar active region around the time of a major flare and coronal mass ejection
• Differential Emission Measure Analysis of Multiple Structural Components of Coronal Mass Ejections in the Inner Corona
• MPI-AMRVAC for Solar and Astrophysics
• MPI-AMRVAC 2.0 for Solar and Astrophysical Applications
• Observing Flux Rope Formation During the Impulsive Phase of a Solar Eruption
• The standard flare model in three dimensions III. Slip-running reconnection properties
• Hot Spine Loops and the Nature of a Late-Phase Solar Flare
• Electric current in flares ribbons: observations and 3D standard model
• Circular Ribbon Flares and Homologous Jets
• Adaptive mesh refinement for conservative systems: multi-dimensional efficiency evaluation
• Eruption of magnetic flux ropes during flux emergence
• Slipping magnetic reconnection during an X-class solar flare observed by SDO/AIA
• Formation of a Double-decker Magnetic Flux Rope in the Sigmoidal Solar Active Region 11520
• Origin and Structures of Solar Eruptions I: Magnetic Flux Rope (Invited Review)
• Slipping Magnetic Reconnection, Chromospheric Evaporation, Implosion, and Precursors in the 2014 September 10 X1.6-Class Solar Flare
• The Relation between Solar Eruption Topologies and Observed Flare Features I: Flare Ribbons
• Formation of Magnetic Flux Ropes during Confined Flaring Well Before the Onset of a Pair of Major Coronal Mass Ejections
• The Influence of Spatial Resolution on Nonlinear Force-Free Modeling
• On the 2012 October 23 circular ribbon flare: emission features and magnetic topology
• X-ray and UV investigation into the magnetic connectivity of a solar flare
• A Non-radial Eruption in a Quadrupolar Magnetic Configuration with a Coronal Null
• The Role of Erupting Sigmoid in Triggering a Flare with Parallel and Large-Scale Quasi-Circular Ribbons
• Topological Analysis of Emerging Bipole Clusters Producing Violent Solar Events
• Helical Kink Instability in a Confined Solar Eruption
• Flux rope, hyperbolic flux tube, and late EUV phases in a non-eruptive circular-ribbon flare
• Study of Two Successive Three-Ribbon Solar Flares on 2012 July 6
• A New Multi-wavelength Solar Telescope: Optical and Near-infrared Solar Eruption Tracer (ONSET)
• On the Characteristics of Footpoints of Solar Magnetic Flux Ropes during the Eruption
• Is flux rope a necessary condition for the progenitor of coronal mass ejections?
• Generation mechanisms of quasi-parallel and quasi-circular flare ribbons in a confined flare
• Triggering Process of the X1.0 Three-ribbon Flare in the Great Active Region NOAA 12192
• Flare Energy Release in the Lower Solar Atmosphere Near the Magnetic Field Polarity Inversion Line

Cited by in corpus (14)

• The role of non-axisymmetry of magnetic flux rope in constraining solar eruptions
• Magnetic helicity and energy budget around large confined and eruptive solar flares
• Evolution of the Toroidal Flux of CME Flux Ropes during Eruption
• An Eruptive Circular-ribbon Flare with Extended Remote Brightenings
• Imaging and spectral study on the null point of a fan-spine structure during a solar flare
• Development of a Confined Circular-cum-parallel Ribbon Flare and Associated Pre-flare Activity
• Magnetic Twists of Solar Filaments
• Evolutionary stages and triggering process of a complex eruptive flare with circular and parallel ribbons
• Properties and Energetics of Magnetic Reconnection: I. Evolution of Flare Ribbons
• Stability of the coronal magnetic field around large confined and eruptive solar flares
• Grow-up of a Filament Channel by Intermittent Small-scale Magnetic Reconnection
• A Hot Cusp-Shaped Confined Solar Flare
• Investigation of two coronal mass ejections from circular ribbon source region: Origin, Sun-Earth propagation and Geo-effectiveness
• Resolving Interchange Reconnection Dynamics in a Fan-Spine-like Topology Observed by Solar Orbiter