Observations of an X-shaped Ribbon Flare in the Sun and Its Three-dimensional Magnetic Reconnection
Abstract
We report evolution of an atypical X-shaped flare ribbon that provides novel observational evidence of three-dimensional (3D) magnetic reconnection at a separator. The flare occurred on 2014 November 9. High-resolution slit-jaw 1330 Å images from the Interface Region Imaging Spectrograph reveal four chromospheric flare ribbons that converge and form an X-shape. Flare brightening in the upper chromosphere spreads along the ribbons toward the center of the “X” (the X-point), and then spreads outward in a direction more perpendicular to the ribbons. These four ribbons are located in a quadrupolar magnetic field. Reconstruction of magnetic topology in the active region suggests the presence of a separator connecting to the X-point outlined by the ribbons. The inward motion of flare ribbons in the early stage therefore indicates 3D magnetic reconnection between two sets of non-coplanar loops that approach laterally, and reconnection proceeds downward along a section of vertical current sheet. Coronal loops are also observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory confirming the reconnection morphology illustrated by ribbon evolution.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 2016
- DOI:
- 10.3847/2041-8205/823/1/L13
- arXiv:
- arXiv:1605.01833
- Bibcode:
- 2016ApJ...823L..13L
- Keywords:
-
- magnetic reconnection;
- Sun: flares;
- Sun: magnetic fields;
- Sun: UV radiation;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- ApJL accepted. Comments are welcome