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In situ evidence for the structure of the magnetic null in a 3D reconnection event in the Earth's magnetotail

Nature Physics volume 2, pages 478–483 (2006)Cite this article

Abstract

Magnetic reconnection is one of the most important processes in astrophysical, space and laboratory plasmas. Identifying the structure around the point at which the magnetic field lines break and subsequently reform, known as the magnetic null point, is crucial to improving our understanding of reconnection. But owing to the inherently three-dimensional nature of this process, magnetic nulls are only detectable through measurements obtained simultaneously from at least four points in space. Using data collected by the four spacecraft of the Cluster constellation as they traversed a diffusion region in the Earth's magnetotail on 15 September 2001, we report here the first in situ evidence for the structure of an isolated magnetic null. The results indicate that it has a positive-spiral structure whose spatial extent is of the same order as the local ion inertial length scale, suggesting that the Hall effect could play an important role in 3D reconnection dynamics.

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Figure 1: The 4-s resolution magnetic field (B ) and plasma velocity (V ) data of C1–C4 (no V2 data) during the interval 05:03–05:04UT on 15 September 2001.
Figure 2: Positions of spacecraft C1, C2 and C4 relative to C3 in GSM coordinates and illustration of the null point surrounded by Cluster satellites.
Figure 3: The high-resolution (0.04 s) magnetic field data of four Cluster spacecraft, and the calculated Poincaré index during 05:03–05:04UT on 15 September 2001.
Figure 4: Schematic diagrams of a positive-spiral-type null and positions of satellites crossing.

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References

  1. Giovanelli, R. G. A theory of chromospheric flares. Nature 158, 81–82 (1946).

    Article  ADS  Google Scholar 

  2. Dungey, J. W. Cosmic Electrodynamics (Cambridge Univ. Press, Cambridge, 1958).

    MATH  Google Scholar 

  3. Dungey, J. W. Interplanetary magnetic field and the auroral zones. Phys. Rev. Lett. 6, 47–48 (1961).

    Article  ADS  Google Scholar 

  4. Dungey, J. W. in Geophysics, The Earth's Environment (ed. Dewitt, C.et al.) 526–531 (Gordon and Breach, New York, 1963).

    Google Scholar 

  5. Parker, E. N. Sweet's mechanism for merging magnetic fields in conducting fluid. J. Geophys. Res. 62, 509–520 (1957).

    Article  ADS  Google Scholar 

  6. Petschek, H. E. in The Physics of Solar Flare (ed. Hess, W. N.) 425–437 (NASA SP-50, NASA, Washington DC, 1964).

    Google Scholar 

  7. Birn, J. et al. Geospace environmental modeling (GEM) magnetic reconnection challenge. J. Geophys. Res. 106, 3715–3719 (2001).

    Article  ADS  Google Scholar 

  8. Phan, T. D. et al. Extended magnetic reconnection at the earth's magnetopause from detection of bi-directional jets. Nature 404, 848–850 (2000).

    Article  ADS  Google Scholar 

  9. Deng, X. H. & Matsumoto, H. Rapid magnetic reconnection in the Earth's magnetosphere generated by whistler waves. Nature 410, 557–559 (2001).

    Article  ADS  Google Scholar 

  10. Øieroset, M. et al. In situ detection of collisionless reconnection in the earth's magnetotail. Nature 412, 414–417 (2001).

    Article  ADS  Google Scholar 

  11. Mozer, F. S., Bale, S. D. & Phan, T. D. Evidence of diffusion regions at a subsolar magnetopause crossing. Phys. Rev. Lett. 89, 015002 (2002).

    Article  ADS  Google Scholar 

  12. Frey, H. U., Phan, T. D., Fuselier, S. A. & Mende, S. B. Continuous magnetic reconnection at Earth's magnetopause. Nature 426, 533–536 (2003).

    Article  ADS  Google Scholar 

  13. Priest, E. R. & Titov, V. S. Magnetic reconnection at three-dimensional null points. Phil. Trans. R. Soc. Lond. A 354, 2951–2992 (1996).

    Article  ADS  MathSciNet  Google Scholar 

  14. Cowley, S. W. H. A qualitatively study of the reconnection between the Earth's magnetic field and an interplanetary field of arbitrary orientation. Radio Sci. 8, 903–913 (1973).

    Article  ADS  Google Scholar 

  15. Lau, Y.-T. & Finn, J. M. Three-dimensional kinematic reconnection in the presence of field nulls and closed field lines. Astrophys. J. 350, 672 (1990).

    Article  ADS  MathSciNet  Google Scholar 

  16. Priest, E. R. & Forbes, T. G. Magnetic Reconnection: MHD Theory and Applications (Cambridge Univ. Press, New York, 2000).

    Book  Google Scholar 

  17. Priest, E. R., Hornig, G. & Pontin, D. I. On the nature of three-dimensional magnetic reconnection. J. Geophys. Res. 108,(2003) doi:10.1029/2002JA009812.

  18. Buchner, J. Three-dimensional magnetic reconnection in astrophysical plasma–-kinetic approach. Astrophys. Space Sci. 264, 25–42 (1999).

    Article  ADS  Google Scholar 

  19. Lui, A. T. Y. Critical issues on magnetic reconnection in space plasmas. Space Sci. Rev. 116, 497–521 (2005).

    Article  ADS  Google Scholar 

  20. Arnold, V. I. Ordinary Differential Equation (Springer, Berlin, New York, 1992).

    Google Scholar 

  21. Wang, J. Vector magnetic field and magnetic activity on the Sun. Fund. Cosmic Phys. 20, 251–382 (1999).

    ADS  Google Scholar 

  22. Greene, J. M. Geometrical properties of 3D reconnecting magnetic fields with nulls. J. Geophys. Res. 93, 8583–8590 (1988).

    Article  ADS  Google Scholar 

  23. Schindler, K., Hesse, M. & Birn, J. General reconnection, parallel electric fields and helicity. J. Geophys. Res. 93, 5547–5557 (1988).

    Article  ADS  Google Scholar 

  24. Wang, X. G. & Bhattacharjee, A. A three-dimensional reconnection model of the magnetosphere: Geometry and kenematics. J. Geophys. Res. 101, 2641–2653 (1996).

    Article  ADS  Google Scholar 

  25. Greene, J. M. & Miller, R. L. Proceedings of the International Symposium in Honor of Bruno Coppi (Report GAA21961) (General Atomics, San Diego, 1995).

    Google Scholar 

  26. Hu, S., Bhattacharjee, A., Dorelli, J. & Greene, J. M. The spherical tearing mode. Geophys. Res. Lett. 31, L19806 (2004).

    Article  ADS  Google Scholar 

  27. Galsgaard, K. & Nordlund, A. Heating and activity of the solar corona: 3. Dynamics of a low-beta plasma with three-dimensional null points. J. Geophys. Res. 102, 231–248 (1997).

    Article  ADS  Google Scholar 

  28. Lau, Y.-T. & Finn, J. M. Magnetic reconnection and the topology of interacting twisted flux tubes. Phys. Plasmas 3, 3983–3997 (1996).

    Article  ADS  Google Scholar 

  29. Pontin, D. I., Hornig, G. & Priest, E. R. in Proceedings of the SOHO 15 Workshop–Coronal Heating (ed. Walsh, R. W.et al.) 507–523 (ESA Publications Division, Noordwijk, 2004).

    Google Scholar 

  30. Parnell, C. E., Smith, J. M., Neukirch, T. & Priest, E. R. The structure of three-dimensional magnetic neutral points. Phys. Plasmas 3, 759–770 (1996).

    Article  ADS  Google Scholar 

  31. Filippov, B. Observation of a 3D magnetic null point in the solar corona. Sol. Phys. 185, 297–309 (1999).

    Article  ADS  Google Scholar 

  32. Aulanier, G. et al. The topology and evolution of the Bastille day flare. Astrophys. J. 540, 1126–1146 (2000).

    Article  ADS  Google Scholar 

  33. Fletcher, L. et al. Evidence for the flare trigger site and three-dimensional reconnection in multiwavelength observations of a solar flare. Astrophys. J. 554, 451–463 (2001).

    Article  ADS  Google Scholar 

  34. Zhao, H., Wang, J., Zhang, J. & Xiao, C. J. A new method of identifying 3D null points in solar vector magnetic fields. Chin. J. Astron. Astrophys. 5, 443–447 (2005).

    Article  ADS  Google Scholar 

  35. Garth, C., Tricoche, X. & Scheuermann, G. in Proceedings of IEEE Visualization '04 (ed. Rushmeier, H.et al.) 329–336 (IEEE Computer Society, Washington DC, 2004).

    Google Scholar 

  36. Ding, W. X. Measurement of internal magnetic field fluctuations in a reversed-field pinch by Faraday rotation. Phys. Rev. Lett. 90, 035002 (2003).

    Article  ADS  Google Scholar 

  37. Escoubet, C. P., Schmidt, R. & Goldstein, M. L. in The Cluster and Phoenix Missions (ed. Escoubet, C. P.et al.) 11–32 (Kluwer Academic, Dordrecht, 1997).

    Google Scholar 

  38. Balogh, A. et al. in The Cluster and Phoenix Missions (ed. Escoubet, C. P.et al.) 65–92 (Kluwer Academic, Dordrecht, 1997).

    Book  Google Scholar 

  39. Reme, H. et al. in The Cluster and Phoenix Missions (ed. Escoubet, C. P.et al.) 303–350 (Kluwer Academic, Dordrecht, 1997).

    Book  Google Scholar 

  40. Greene, J. M. Locating three-dimensional roots by a bisect ion method. J. Comput. Phys. 98, 194–198 (1992).

    Article  ADS  MathSciNet  Google Scholar 

  41. Cai, D. S., Li, Y. T., Ichikawai, T., Xiao, C. J. & Nishikawa, K. Visualization and criticality of magnetotail field topology in a three-dimensional particle simulation. Earth, Planets Space 53, 1011 (2001).

    Article  ADS  Google Scholar 

  42. Sonnerup, B. U. O. & Scheible, M. in Analysis Methods for Multi-Spacecraft Data. (eds Paschmann, G. & Daly, P. W.) 185–220 (ESA Publications Division, Noordwijk, 1998).

    Google Scholar 

  43. Khurana, K. K. et al. Accurate determination of magnetic field gradients from four-point vector measurements-II: use of nutral constraints on vector data obtained from four spinning spacescraft. IEEE Trans. Magn. 32, 5193–5205 (1996).

    Article  ADS  Google Scholar 

  44. Chanteur, G. in Analysis Methods for Multi-Spacecraft Data (eds Paschmann, G. & Daly, P. W.) 349–369 (ESA Publications Division, Noordwijk, 1998).

    Google Scholar 

  45. Xiao, C. J. et al. Multiple magnetic reconnection events observed by Cluster: current calculating. Chin. J. Geophys. 47, 635–643 (2004).

    Article  ADS  Google Scholar 

  46. Wang, X. G., Bhattacharjee, A. & Ma, Z. W. Collisionless reconnection: effects of Hall current and electron pressure gradient. J. Geophys. Res. 105, 27633 (2000).

    Article  ADS  Google Scholar 

  47. Wang, X. G., Bhattacharjee, A. & Ma, Z. W. Scaling of collisionless forced reconnection. Phys. Rev. Lett. 87, 265003 (2001).

    Article  ADS  Google Scholar 

Download references

Acknowledgements

This work is supported by the NSFC Programs (Grant Nos 40390150, 4050421, 10233050, 10575018, 40536030, 40425004, and 40228006) and the China Key Research Project (Grant No. G200000784), as well as the China Double Star-Cluster Science Team. The authors also thank D. S. Cai, E. R. Priest, and G. P. Zhou for helpful discussions and suggestions, as well as H. Schwarzl for producing the intercalibrated FGM data.

Author information

Authors and Affiliations

  1. National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012, China

    C. J. Xiao, H. Zhao & J. X. Wang

  2. State Key Lab of Materials Modification by Laser, Ion, and Electron Beams, Dalian University of Technology, Dalian, 116024, China

    X. G. Wang

  3. School of Earth and Space Sciences, Peking University, Beijing, 100871, China

    Z. Y. Pu & S. Y. Fu

  4. Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031, China

    Z. W. Ma

  5. Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California, USA

    M. G. Kivelson

  6. CSSAR, Chinese Academy of Sciences, Beijing, 100080, China

    Z. X. Liu

  7. Center for Atmospheric Research, University of Massachusetts Lowell, MA, 01854-3629, USA

    Q. G. Zong

  8. IGEP, Technische Universität Braunschweig, Braunschweig, Germany

    K. H. Glassmeier

  9. Department of Physics, Imperial College of Science, Technology and Medicine, London, UK

    A. Balogh

  10. MPI for Solar System Research, Katlenburg-Lindau, Germany

    A. Korth

  11. Centre d'Etude Spatiale des Rayonnements, BP 4346, 31028, Toulouse, Cedex 4, France

    H. Reme

  12. ESA/ESTEC, Postbus 299, 2200, AG Noordwijk, The Netherlands

    C. P. Escoubet

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  1. C. J. Xiao
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Correspondence to Z. Y. Pu.

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Xiao, C., Wang, X., Pu, Z. et al. In situ evidence for the structure of the magnetic null in a 3D reconnection event in the Earth's magnetotail. Nature Phys 2, 478–483 (2006). https://doi.org/10.1038/nphys342

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