Articles | Volume 26, issue 10
Ann. Geophys., 26, 3017–3024, 2008

Special issue: SOHO 20 – Transient events on the Sun and in the...

Ann. Geophys., 26, 3017–3024, 2008

  15 Oct 2008

15 Oct 2008

Magnetic reconnection processes induced by a CME expansion

A. Bemporad1,*, G. Poletto2, F. Landini3, and M. Romoli3 A. Bemporad et al.
  • 1INAF – Torino Astrophysical Observatory, via Osservatorio 20, 10025 Pino Torinese (TO), Italy
  • 2INAF – Arcetri Astrophysical Observatory, L.go E. Fermi 5, 50125 Firenze, Italy
  • 3Dept. of Astronomy and Space Science, University of Firenze, L.go E. Fermi 2, 50125 Firenze, Italy
  • *Work partially made while at the Arcetri Astrophysical Observatory, L.go E. Fermi 5, 50125 Firenze, Italy

Abstract. On 10–11 December 2005 a slow CME occurred in the Western Hemisphere in between two coronal streamers. SOHO/MDI magnetograms show a multipolar magnetic configuration at the photosphere: a complex of active regions located at the CME source and two bipoles at the base of the lateral coronal streamers. White light observations reveal that the CME expansion affects both of them and induces the release of plasma within or close to the nearby streamers. These transient phenomena are possibly due to magnetic reconnections induced by the CME expansion and occurring inside the streamer current sheet or between the CME flanks and the streamer.

These events have been observed by the SOHO/UVCS with the spectrometer slit centered at 1.8 R over about a full day. In this work we focus on the interaction between the CME and the streamer: the UVCS spectral interval included UV lines from ions at different temperatures of maximum formation such as O VI, Si XIII and Al Xi. These data gave us the opportunity to infer the evolution of plasma temperature and density at the reconnection site and adjacent regions. These are relevant to characterize secondary reconnection processes occurring during a CME development.