Three-dimensional Structure of Coronal Mass Ejections from LASCO Polarization Measurements

Abstract

The three-dimensional structure of a coronal mass ejection (CME) is essential information for understanding the process by which they are ejected from the Sun. Coronagraphic measurements readily provide information on the structure of CMEs in the plane of the sky. It has been known for some time that polarization measurements can provide information on the position of coronal plasmas out of the plane of the sky. Recently, T. G. Moran & J. M. Davila have shown that polarimetric measurements with the Large Angle and Spectrometric Coronagraph (LASCO) can be used to determine the three-dimensional structure of a CME with considerable definition. We have examined a series of high-cadence (1 hr) LASCO polarization measurements obtained during 2002 and discuss the analysis of two particularly well observed events. One event indicates that the CME structure is that of a rising arcade of loops, while the other appears to consist of a flux-rope type of structure. Because we have examined a large, relatively high cadence set of LASCO observations, we have been able to select events that provide significantly greater definition of CME structure than previously possible.