Numerical Simulations of Dome-Shaped EUV Waves from Different Active-Region Configurations
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Recently, 3D STEREO observations explained the 3D structure of EUV waves. Patsourakos and Vourlidas (Astrophys. J. 700, L182, 2009), Veronig et al. (Astrophys. J. 716, L57, 2010) and Selwa, Poedts, and DeVore (Astrophys. J. 747, L21, 2012) reported on the dome-shaped EUV waves resulting from different events. Here, we model, by means of 3D MHD simulations, the formation of dome-shaped EUV waves in rotating active regions (ARs). The numerical simulations are initialized with idealized (multi-)dipolar coronal (low β) configurations. Next, we apply a sheared rotational motion to the central parts of all the positive and negative flux regions at the photospheric boundary. As a result, the flux tubes connecting the flux sources become twisted. We find that in all the studied configurations of idealized ARs, the rotating motion results in a dome-shaped structure originating from the AR. However, the shape of the dome depends on the initial configuration (topology of the AR). The initial stage of the wave evolution consists of multiple fronts that later merge together forming a single wave. The observed EUV wave propagates nearly isotropically on the disk and also in the upward direction. We remark that the initial stage of the evolution is determined by the driver and not caused by a magnetic reconnection event. At a later stage, however, the wave propagates freely. We study the different wave properties resulting from different driver speeds and find that independent of the initial AR topology the 3D dome-shaped wave is excited in the system. The symmetry of the 3D dome depends on the topology of the AR and on the duration of the driver. The EUV wave triggered is independent of the temporal profile of the driver. However, the properties of the wave (speed, sharpness of the cross-section, etc.) depend on the type of the trigger.
KeywordsActive regions, models Corona, structures Flares, pre-flare phenomena Flares, waves EUV waves, propagation
MS expresses thanks to Dr. Leon Ofman and the referee for their comments. MS’s work was supported by the SIDC Data Exploitation (ESA Prodex 9 C 90347) project. Part of her work was supported by the European Commission under the Solaire Marie Curie Training Network. SP’s work was supported by the projects GOA/2009-009 (KU Leuven), G.0729.11 (FWO-Vlaanderen) and C 90347 (ESA Prodex 9). Financial support also was provided by the European Commission’s Seventh Framework Programme (FP7) under grant agreements SOLSPANET (project 269299, www.solspanet.eu ), SPACECAST (project 262468, fp7-spacecast.eu), and SWIFF (project 263340, www.swiff.eu ). CRD’s work was supported by NASA. For the computations we used the infrastructure of the VSC Flemish Supercomputer Center, funded by the Hercules Foundation and the Flemish government department EWI.
- Brown, D.: Rotating sunspots spin up a super solar flare, PHYSorg. com, 21 April 2011. http://www.physorg.com/news/2011-04-rotating-sunspots-super-solar-flare.html.