Ulysses Meeting abstract

Magnetic structures and discontinuities at CME boundaries: Ulysses observations
R. Kilmurray, A. Balogh, R.J. Forsyth, J. Glover

AGU Fall Meeting, San Francisco, 8-12 December 1997

Abstract: We present in this paper a study of the magnetic structures in the boundary regions of over 50 CMEs observed by Ulysses in its first five years of operation. The interaction between CMEs and the ambient solar wind generates complex boundary regions which have not been fully characterized. One difficulty is the absence of sufficiently clear solar wind and magnetic field signatures which would allow to determine unambiguously and with high time resolution the interface between CME ejecta and the ambient solar wind. Depending on the CME parameters and the prevailing conditions in the solar wind, as well as the geometry of the observations, the boundary region contains discontinuities and planar magnetic structures; there is also evidence in some cases for field line draping. In this study, we present the different characteristics of the boundary regions associated with

  1. CMEs that were associated with fast shocks,
  2. others that were not,
  3. those with a clear signature of magnetic clouds, and
  4. those in which the flux rope structure was unclear.
A search for slow shocks in regions ahead of CMEs has yielded only one candidate, in a situation when two consecutive CMEs were clearly interacting. While it is difficult to draw general conclusions in view of the diversity of characteristic features in the CME boundary regions, the Ulysses observations highlight the main features of the CME interaction with the solar wind.
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Last changed 10th September 1997 by Tim Horbury.