Remote sensing of the solar site of interchange reconnection associated with the May 1997 magnetic cloud

Abstract

The direction of suprathermal electron flux on open magnetic field lines in the 15 May 1997 magnetic cloud is used to predict the solar location of the interchange reconnection that released one end of what presumably were doubly connected field lines in the coronal mass ejection (CME) of origin on 12 May. A search for an X‐ray signature of the interchange reconnection in the predicted location reveals a long‐lasting arched structure stretching from high above the CME site to the northern polar coronal hole. At the edge of the coronal hole, coincident with the X‐ray feature, are previously reported extreme ultraviolet brightenings (“crinkles”). The observations are consistent with a CME flux rope forming in a near‐quadrupolar configuration while overhead open field lines reconnect with the rising, closed, rope fields to open one leg of the rope loop. The pattern is similar to the breakout model except there are no closed overhead field lines through which the rising flux rope must break out. The near‐quadrupolar source appears to be responsible for the mismatch between the polarity of the flux rope observed at 1 AU and the sector in which it was embedded. Spacecraft interception of the leg rather than the apex of the flux rope loop may be responsible for the mismatch between the low inclination of the cloud axis and the high inclination predicted from the preexisting filament and magnetic configuration at the source.