Abstract
Detection of a separator line that connects magnetic nulls and the determination of the dynamics and plasma environment of such a structure can improve our understanding of the three-dimensional (3D) magnetic reconnection process1,2,3,4,5,6,7,8,9. However, this type of field and particle configuration has not been directly observed in space plasmas. Here we report the identification of a pair of nulls, the null–null line that connects them, and associated fans and spines in the magnetotail of the Earth using data from the four Cluster spacecraft. With di and de designating the ion and electron inertial lengths, respectively, the separation between the nulls is found to be ∼0.7±0.3di and an associated oscillation is identified as a lower-hybrid wave with wavelength ∼de. This in situ evidence of the full 3D reconnection geometry and associated dynamics provides an important step towards establishing an observational framework of 3D reconnection.
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Acknowledgements
This work is supported by the NSFC Programs (grant Nos 40390150, 40504021, 10233050, 10575018, 40536030, 40425004 and 40228006) and the National Basic Research Programme of China (grant No 2006CB806300), as well as the CAS Project KJCX2-YW-T04 and the China Double Star-Cluster Science Team. C.J.X. also thanks A. Grinsted at the University of Lapland for supporting the MatLab wavelet coherence package.
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C.J.X., X.G.W., and Z.Y.P. are first authors with equal contributions to theoretical and data analysis. Z.W.M. has also made important contributions to the paper, and H.Z., G.P.Z. and J.X.W. have developed analysis tools and participated in the analysis. Other coauthors have provided the Cluster observation data and been involved in discussions. M.G.K. has also made significant contributions to the final revision of the paper.
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Xiao, C., Wang, X., Pu, Z. et al. Satellite observations of separator-line geometry of three-dimensional magnetic reconnection. Nature Phys 3, 609–613 (2007). https://doi.org/10.1038/nphys650
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DOI: https://doi.org/10.1038/nphys650
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