Abstract
Hα observations of solar active region NOAA 10501 on 2003 November 20 revealed a very uncommon dynamic process: during the development of a nearby flare, two adjacent elongated filaments approached each other, merged at their middle sections, and separated again, thereby forming stable configurations with new footpoint connections. The observed dynamic pattern is indicative of slingshot reconnection between two magnetic flux ropes. We test this scenario by means of a three-dimensional zero β magnetohydrodynamic simulation, using a modified version of the coronal flux rope model by Titov and Demoulin as the initial condition for the magnetic field. To this end, a configuration is constructed that contains two flux ropes which are oriented side-by-side and are embedded in an ambient potential field. The choice of the magnetic orientation of the flux ropes and of the topology of the potential field is guided by the observations. Quasi-static boundary flows are then imposed to bring the middle sections of the flux ropes into contact. After sufficient driving, the ropes reconnect and two new flux ropes are formed, which now connect the former adjacent flux rope footpoints of opposite polarity. The corresponding evolution of filament material is modeled by calculating the positions of field line dips at all times. The dips follow the morphological evolution of the flux ropes, in qualitative agreement with the observed filaments.
Highlights
Magnetic reconnection is a key process at work in dynamic energy release events in the solar corona, occurring on a large variety of spatial scales (e.g., Shibata 1999)
MHD cannot capture the kinetic processes at work in reconnection, such simulations are important for understanding the physics involved and for modeling, at least qualitatively, the energy release and structural magnetic field changes associated with reconnection in the corona
We focus on reconnection between large-scale coronal flux ropes, which has been suggested as a mechanism for compact flares (e.g., Hanaoka 1997; Nishio et al 1997) and to occur in some flares associated with coronal mass ejections (CMEs) (Chandra et al 2006; Kliem et al 2010)
Summary
Magnetic reconnection is a key process at work in dynamic energy release events in the solar corona, occurring on a large variety of spatial scales (e.g., Shibata 1999). In order to study the conditions for flux rope reconnection, Linton et al (2001) simulated the collision of magnetically isolated cylindrical ropes for convection zone conditions, using an initial stagnation-point flow and periodic boundary conditions They found several types of reconnection, depending on the sign of flux rope twist and on the angle between colliding field lines. We present an MHD simulation of three-dimensional flux rope reconnection that qualitatively reproduces the abovementioned filament interaction It complements the work of Linton et al (2001) by considering coronal conditions, i.e., a zero β environment, arched and line-tied flux ropes embedded in a potential field, and photospheric flows
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