Abstract
Abstract. In order to analize the influence of a Coronal Mass Ejection (CME) on the coronal streamer belt, we made 3-D reconstructions of the electron density in the corona at heliospheric distances from 1.5 to 4 R⊙ for periods before and after a CME occured. The reconstructions were performed using a tomography technique. We studied two CME cases: (i) a slow CME on 1 June 2008; (ii) two fast CMEs on 31 December 2007 and 2 January 2008. For the first case of slow CME, it was found: (i) the potential magnetic field configuration in the CME initiation region before the CME does not agree with the coronal density structure while after the CME the agreement between the field and density is much better. This could be manifistation of that that the field was non-potential before the CME and after the CME the field relaxes towards a more potential state. (ii) It was shown that the dimming caused by the slow CME is not due to rotation of the corona and a line-of-sight (LOS) effect but a streamer blow out effect took place.
Highlights
Coronal Mass Ejections (CME) plays an important role for space weather research
The CME locations were determined by performing 3-D triangulations from simultaneous STEREO A and B images of SECCHI/COR1 using the IDL SolarSoft routine scc-measure, and it has been verified with SECCHI/EUVI images if the source locations of the CME appear on solar disk in either STEREO A and B
Llebaria et al (2006) made a statistical analysis of the interaction of CMEs with the streamer belt and have found that 72 % cases of slow CMEs caused dimming in the streamer while this effect occured only for 18 % of the investigated fast CMEs
Summary
The latest progress in these measurements (Lin et al, 2004; Tomczyk et al, 2008; Judge, 2007) and the vector tomography technique (Kramar et al, 2006; Kramar and Inhester, 2007) gives a hope for increasing our knowledge about the coronal magnetic field. Vector magnetograms from the photosphere have became available, which in principle supply all the information necessary for a non-linear force-free field extrapolation of the surface data into the solar corona (Wiegelmann et al, 2005; Wiegelmann, 2008). In the present paper we study the pre- and post-CME coronal electron density structure and compared it with the potential field source surface (PFSS) models for the correspondent periods. The reconstructions of the coronal electron density were performed using a tomography technique
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