Ulysses paper

J. Geophys. Res, 105, A6, 12713-12724, 2000.

Abstract:
An analysis is presented of planar magnetic structures (PMSs) detected in the solar wind by the Ulysses spacecraft between its launch in October 1990 and the end of 1998. In all, 667 such structures were found, with duration between 6 hours (the minimum in the search algorithm) and 66 hours. The total amount of magnetometer data found to represent planar periods accounted for 9% of all data returned from the instrument during 1990-8. PMSs are found to be a common occurrence within corotating interaction regions. Around one-fifth of PMSs can probably be accounted for by the passage of shocks through the solar wind, leading to alignmemt and amplification of pre-existing features. Heliospheric current sheet crossings were found to be close to around 50% of PMSs. The result thus favour several previously proposed PMS formation mechanisms. After other causes of PMSs such as draping around the interplanetary counterparts of coronal mass ejecta are taken into account, there still remains a sizeable minority of events that have no obvious association with other solar wind features. It is suggested that some of these unexplained PMSs may have been caused by draping around transient features, and had remained in the solar wind when the signature of the transient was no longer recognisable.

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