Observations on the Magnetic Disconnections of a Magnetic Cloud from the Sun through Magnetic Reconnection

Most coronal mass ejections (CMEs) originally exhibit closed magnetic flux rope (MFR) structures near the Sun. Moreover, the amount of magnetic field magnitude in the heliosphere can continually increase when CMEs propagate from the Sun to interplanetary space. To solve the problem of increased magnetic field magnitude, the closed field lines of MFRs should be opened and disconnected through magnetic reconnections. Here, we report a magnetic cloud (MC) associated with a magnetic reconnection exhaust measured by Wind over the period of 2001 October 31 to November 1. Observations of unidirectional suprathermal electron strahls revealed that part of the field lines before the rear boundary of the MC was opened. The magnetic reconnection event was disconnecting the opened field lines of the MC by merging with open field lines after the MC. These observations indicated that MFRs could be opened or disconnected in no particular order.