The orientation of flux rope CMEs from the corona to 1 AU

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Title: The orientation of flux rope CMEs from the corona to 1 AU
Author: Käki, Sebastian
Contributor: Helsingin yliopisto, Matemaattis-luonnontieteellinen tiedekunta, Fysiikan laitos
Thesis level:
Abstract: Coronal mass ejections (CMEs) are ejections of plasma and magnetic flux from the Sun. These eruptions are large in size and they propagate over large distances in the heliosphere. If a CME is directed towards the Earth it can cause major space weather disturbances. Thus it is important to know whether a CME will hit the magnetosphere of the Earth and what kind of disturbances it could cause. CMEs contain large-scale twisted magnetic fields called flux ropes. Information about the orientation and the structure of the flux rope is crucial in determining its space weather effects. This thesis is focused on the determination of the orientation and the direction of flux rope CMEs from the corona all the way to the orbit of the Earth. An overview of a number of methods to obtain the necessary flux rope parameters both from remote sensing and in situ measurements is given. In particular, a technique combining the remote and in situ observations with a Sun-to-Earth propagation model for the CME is described in detail. In this thesis, the technique is used to study the propagation of a slow and a fast CME and the results are compared with each other and with earlier studies on the subject. The direction and amount of deflections and rotation were found to be consistent with the earlier results. In addition, differences in the proportional deflections before and after 20 Solar radii with respect to the total deflections were found between the fast and the slow case.
Date: 2015-06-09
Discipline: Teoreettinen fysiikka

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