Sophie Masson, Patrick McCauley, Leon Golub, Katharine K. Reeves, Ed DeLuca
Magnetic reconnection between open and closed magnetic field in the corona is believed to play a crucial role in the corona / heliosphere coupling. At large scale, the exchange of open /closed connectivity is expected to occur in pseudo- streamer structures. However, there is neither clear observational evidence of how such coupling occurs in pseudo-streamers, nor evidence for how the magnetic reconnection evolves. Using a newly-developed technique, we enhance the off-limb magnetic fine structures observed with AIA and identify a pseudo-streamer-like feature located close to the northern coronal hole. We first verify that the magnetic topology related to the observation is a null-point topology surrounded by open magnetic field of the coronal hole. We then compare the evolution of the observed pseudo-streamer fine structure with the location of strong currents, i.e. in the region of energy dissipation, with the dynamics of the magnetic field resulting from the interchange reconnection obtained in the fully 3D MHD simulation. The morphological and dynamical similarities between the pseudo-streamer observations and the results from the simulation strongly suggest that the evolution of the pseudo-streamer is caused by interchange reconnection in a null-point topology that is embedded in Quasi-Separatrix layers. Besides identifying the mechanism at work in the large scale coupling between open and closed field, our results highlight that the interchange reconnection in pseudo-streamers is a gradual physical process and differs from the impulsive reconnection of the solar-jet model.
View original:
http://arxiv.org/abs/1301.0740
No comments:
Post a Comment