Abstract
AbstractActive regions (ARs), involved in the Halloween events during October-November 2003, were the source of unusual activity during the following solar rotation. The flares on 18-20 November 2003 that occur in the AR NOAA10501 were accompanied by coronal mass ejections associated to some particularly geoeffective magnetic clouds.Our analysis of the magnetic flux and helicity injection revealed that a new emerging bipole and consequent shearing motions continuously energized the region during its disk passage. The stored energy was eventually released through the interaction of the various systems of magnetic loops by several magnetic reconnection events. Active events on November 18 (filament eruptions and CMEs) were originated by shearing motions along a section of the filament channel that injected magnetic helicity with sign opposite to that of the AR. Two homologous flares, that occurred on November 20, were apparently triggered by different mechanisms as inferred from the flare ribbons evolution (filament eruption and CMEs). We studied in detail the behaviour of two North-South oriented filaments on November 20 2003. They merged and split following a process suggestive of ‘sling-shot’ reconnection between two coronal flux ropes. We successfully tested this scenario in a 3D MHD simulation that is presented in this paper.
Highlights
It is widely accepted that three phenomena, flare, CME, and filament eruption, are different observational manifestations of a sudden and violent disruption of the coronal magnetic field, often referred to as “solar eruption”
Observations and Results Active region NOAA 10501 was one of the most complex and eruptive regions during the decay phase of solar cycle 23. This Active regions (ARs) is the successor of the very flare productive active region NOAA 10484, as it was named in the previous solar rotation
The early events on 18 November, 2003, have been extensively studied (Gopalswamy et al 2005; Yurchyshyn, et al 2005; Mostl et al 2008; Srivastava et al 2009; Chandra et al 2010a). The peculiarity of this AR on that day was that it presented regions with different magnetic helicity signs, as was discussed by Chandra et al (2010a)
Summary
It is widely accepted that three phenomena, flare, CME, and filament eruption, are different observational manifestations of a sudden and violent disruption of the coronal magnetic field, often referred to as “solar eruption” The early events on 18 November, 2003, have been extensively studied (Gopalswamy et al 2005; Yurchyshyn, et al 2005; Mostl et al 2008; Srivastava et al 2009; Chandra et al 2010a) The peculiarity of this AR on that day was that it presented regions with different magnetic helicity signs, as was discussed by Chandra et al (2010a). Nearby the flare region two adjacent, elongated north-south oriented filaments merged and separated again; after this process two filaments with different footpoint connections were observed (Figure 4) This process was most probably forced mainly by the rotational motion of one polarity about the other in an emerging bipole at the center of the AR. The newly formed southern filament erupted later on, triggering a CME which was the source of an ICME on November 22, 2003
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