Magnetic reconnection in the solar wind: Filamentary currents in a multi-layered exhaust region at an ICME sheath—ejecta boundary

In the solar wind, a bifurcated current sheet is often observed in a reconnection outflow region as predicted by the original Petchek reconnection model, with the detailed exhaust structure becoming more complex when asymmetries between reconnecting plasmas are present. Here we present the first multi-spacecraft mission in-situ observations of a solar wind reconnection exhaust populated with filamentary (Hall) currents at an interplanetary coronal mass ejection (ICME) sheath—ejecta boundary. At the ICME sheath—ejecta boundary, asymmetric inflow conditions control reconnection, a relatively hot and dense plasma of the sheath coupling with the sparse low-beta ejecta plasma. These novel high-resolution observations demonstrate a multi- layered exhaust, and speak for the opportunities that future missions, such as HelioSwarm, and Parker Solar Probe and Solar Orbiter open for investigating magnetic reconnection in the solar wind.