Coronal Magnetic Reconnection Driven by CME Expansion - the 2011 June 7 Event

Van Driel Gesztelyi, Lídia and Baker, D. and Török, T. and Pariat, E. and Green, L. M. and Williams, D. R. and Carlyle, J. and Valori, G. and Démoulin, P. and Kliem, B. and Long, D. M. and Matthews, S. A. and Malherbe, J. -M. (2014) Coronal Magnetic Reconnection Driven by CME Expansion - the 2011 June 7 Event. ASTROPHYSICAL JOURNAL, 788 (1). ISSN 1538-4357

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Abstract

Coronal mass ejections (CMEs) erupt and expand in a magnetically structured solar corona. Various indirect observational pieces of evidence have shown that the magnetic field of CMEs reconnects with surrounding magnetic fields, forming, e.g., dimming regions distant from the CME source regions. Analyzing Solar Dy- namics Observatory (SDO) observations of the eruption from AR 11226 on 2011 June 7, we present the first direct evidence of coronal magnetic reconnection between the fields of two adjacent ARs during a CME. The observations are presented jointly with a data-constrained numerical simulation, demonstrating the forma- tion/intensification of current sheets along a hyperbolic flux tube (HFT) at the interface between the CME and the neighbouring AR 11227. Reconnection resulted in the formation of new magnetic connections between the erupting magnetic structure from AR 11226 and the neighboring active region AR 11227 about 200 Mm from the eruption site. The onset of reconnection first becomes apparent in the SDO/AIA images when filament plasma, originally contained within the erupting flux rope, is re-directed towards remote areas in AR 11227, tracing the change of large-scale magnetic connectivity. The location of the coronal reconnection region be- comes bright and directly observable at SDO/AIA wavelengths, owing to the presence of down-flowing cool, dense (1010 cm−3) filament plasma in its vicinity. The high-density plasma around the reconnection region is heated to coronal temperatures, presumably by slow-mode shocks and Coulomb collisions. These results pro- vide the first direct observational evidence that CMEs reconnect with surrounding magnetic structures, leading to a large-scale re-configuration of the coronal magnetic field.

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