Observations of Magnetic Reconnection in the Turbulent High-Speed Solar Wind

The high-speed solar wind that originates in coronal holes is permeated by evolved, Alfvénic-type fluctuations associated with MHD turbulence. We have used high temporal resolution (3 s) plasma and magnetic field measurements by the Wind spacecraft at 1 AU to identify and study Petschek-like reconnection exhausts in this turbulent flow for the first time. Despite the fact that the turbulent cascade produces numerous thin current sheets at 1 AU, such exhausts are relatively rare; we have identified only 34 reconnection exhausts in 1358 hr of high-speed solar wind data. With three exceptions, each exhaust was embedded within a relatively sharp, outward-propagating Alfvénic fluctuation. Local field shear angles across these reconnection exhausts ranged from 24° to 160°, with average and median values being ~90°. The vast majority (88%) of these exhausts were narrower than 4 × 10 4 km and were convected past the spacecraft in <66 s. Multispacecraft observations indicate that current sheets, and thus also reconnection X-lines, in the turbulent, high-speed wind are considerably more localized than in the low-speed wind or in interplanetary coronal mass ejections. The Wind observations demonstrate that reconnection is one way in which solar wind turbulence is dissipated and the high-speed wind heated far from the Sun, although it is not yet clear how effective reconnection is overall in this regard.