Investigation of a confined C-class flare in an arch filament system close to a regular sunspot

Abstract

A moderate C1.1 class confined flare is investigated here, which occurred on 2013 September 24 at 22:56~UT, in an arch filament system close to a regular, unipolar sunspot. Spectro-polarimetric observations from the Tenerife Infrared Polarimeter at the 70 cm German Vacuum Tower Telescope were combined with data from the Helioseismic Magnetic Imager and the Atmospheric Imaging Assembly to identify the processes that triggered the flare. The legs of this arch filament were anchored in the leading sunspot and the network flux region of opposite polarity. The flare was driven by small-scale, flux cancellation at the weak neutral line underlying the arch filament which resulted in two small flaring events within an hour of the C1.1 flare. Flux cancellation was facilitated by the moat flow from the leading sunspot wherein small-scale magnetic fragments stream towards patches of pre-existing flux. The cancellation of flux led to the destabilization of the arch filament which was seen as an increase in the twist along the arch filament. The horizontal fields across the weak neutral line decay faster which cannot prevent the filament from rising that results in a two-ribbon flare at the neutral line. The arch filament unwinds as it rises, but is confined by the higher, overlying fields between the two polarities of the active region that decay much more slowly.

arXiv commentAccepted for publication in Journal of Geophysical Research - Space Physics. 22 Pages, 10 Figures

References in corpus (28)

• Torus instability
• Confined and ejective eruptions of kink-unstable flux ropes
• Ideal kink instability of a magnetic loop equilibrium
• Driving major solar flares and eruptions: a review
• Why Is the Great Solar Active Region 12192 Flare-Rich But CME-Poor?
• Different Power-law Indices in the Frequency Distributions of Flares with and without Coronal Mass Ejections
• Photospheric flux cancellation and associated flux rope formation and eruption
• A Comparative Study Between Eruptive X-class Flares Associated with Coronal Mass Ejections and Confined X-class Flares
• Eruption of magnetic flux ropes during flux emergence
• High-resolution observations of flare precursors in the low solar atmosphere
• A Comparative Study of Confined and Eruptive Flares in NOAA AR 10720
• How did a Major Confined Flare Occur in Super Solar Active Region 12192?
• Formation of Magnetic Flux Ropes during Confined Flaring Well Before the Onset of a Pair of Major Coronal Mass Ejections
• Twist Accumulation and Topology Structure of a Solar Magnetic Flux Rope
• Confined Flares in Solar Active Region 12192 from 2014 October 18 to 29
• Statistical Analysis of Torus and Kink Instabilities in Solar Eruptions
• Why is a flare-rich active region CME-poor?
• A magnetic reconnection event in the solar atmosphere driven by relaxation of a twisted arch filament system
• Small-scale chromospheric jets above a sunspot light bridge
• Rapid buildup of a magnetic flux rope during a confined X2.2 class flare in NOAA AR 12673
• Relationship between eruptions of active-region filaments and associated flares and CMEs
• Moat flow in the vicinity of sunspots for various penumbral configurations
• High-Resolution Observations of Flares in an Arch Filament System
• On the Relationship Between Coronal Magnetic Decay Index and CME Speed
• Magnetic Flux Change and Cancellation Associated with X-class and M-class Flares
• A Comparative Study of the Eruptive and Non-Eruptive Flares Produced by the Largest Active Region of Solar Cycle 24
• A comparative study between a failed and a successful eruption initiated from the same polarity inversion line in AR 11387
• The association between sunspot magnetic fields and superpenumbral fibrils