RECONNECTION ON OPEN-FIELD LINES AHEAD OF CORONAL MASS EJECTIONS

Plasma and magnetic field signatures from 29 November 1990 indicate th at the Ulysses spacecraft passed through a series of interplanetary st ructures that were most likely formed by magnetic reconnection on open field lines ahead of a coronal mass ejection (CME). This reconnection changed the magnetic topology of the upstream region by converting no rmal open interplanetary magnetic field into a pair of regions: one ma gnetically disconnected from the Sun and the other, a tongue, connecte d back to the Sun at both ends. This process provides a new method for producing both heat flux dropouts and counterstreaming suprathermal e lectron signatures in interplanetary space. In this paper we expand up on the 29 November case study and argue that reconnection ahead of CME s should be less common at high heliolatitudes.