Observation of Interplanetary Slow Shock Pair Associated with Reconnection Exhaust in Magnetic Cloud Boundary Layer

Abstract

Magnetic reconnection is prevalent in the solar wind and is usually associated with interplanetary coronal mass ejections. We examined a Petschek-like reconnection exhaust (RE) in the front boundary of a magnetic cloud observed by the WIND spacecraft on 1998 June 2 and presented the first observation of a slow shock pair bounding the Petschek-like outflow jet in the interplanetary space. The whole structure contained an Alfvénic accelerated outflow and a pair of reverse slow shocks. The Alfvénic accelerated outflow was identified by Walén analysis. Rankine–Hugoniot relations were applied to confirm the slow shocks bounding the RE. Both shocks strictly satisfied the characteristics of slow shocks: (1) the intermediate Alfvén Mach numbers were both below unit in the up/downstream region; (2) the slow Mach number was above unit in the upstream side but below unit in the downstream side. Plasma was compressed and heated across the trailing slow shock, especially in the shock jump layer that has a temperature 2.4 times that of the upstream.