A magnetic reconnection X-line extending more than 390 Earth radii in the solar wind
Publication date: 12 January 2006
Authors: Phan, T.D. et al.
Copyright: Nature Publishing Group
Magnetic reconnection in a current sheet is a magnetic to particle energy conversion process that is important in many laboratory, space and astrophysical contexts. It is not presently known whether reconnection is fundamentally a process that can occur over an extended region in space or whether it is patchy and unpredictable in nature. Frequent reports of small-scale flux ropes and flow channels in Earth's magnetosphere associated with reconnection raise the possibility that reconnection is intrinsically patchy, each reconnection region extending at most a few Earth radii (RE) even though the associated current sheets span many tens or hundreds of RE. Here we report three spacecraft observations of accelerated flow associated with reconnection in a current sheet embedded in the solar wind flow where the reconnection line extended at least 390 RE (or 2.5 million km). Observations of this and 27 similar events imply that reconnection is fundamentally large scale. Patchy reconnection observed in the magnetosphere is likely to be a geophysical effect associated with fluctuating boundary conditions rather than a fundamental property of reconnection. Our observations also reveal, surprisingly, that reconnection can operate in a quasi-steady-state manner even when undriven by the external flow.Link to publication