Determining the azimuthal properties of coronal mass ejections from multi-spacecraft remote-sensing observations with stereo secchi

TL;DR

This paper presents models to analyze the azimuthal properties of CMEs using multi-spacecraft observations, revealing their deflection, expansion, and deviations from self-similar evolution, emphasizing the value of multiple satellites for space weather prediction.

Contribution

Introduces two simple geometric models to derive CME azimuthal properties from multi-spacecraft observations, enhancing understanding of CME dynamics.

Findings

Most CMEs observed are consistent with radial outward motion.

Able to derive CME cross-sections and deviations from self-similar expansion.

Highlights the importance of multiple satellites for accurate space weather forecasting.

Abstract

We discuss how simultaneous observations by multiple heliospheric imagers can provide some important information about the azimuthal properties of Coronal Mass Ejections (CMEs) in the heliosphere. We propose two simple models of CME geometry that can be used to derive information about the azimuthal deflection and the azimuthal expansion of CMEs from SECCHI/HI observations. We apply these two models to four CMEs well-observed by both STEREO spacecraft during the year 2008. We find that in three cases, the joint STEREO-A and B observations are consistent with CMEs moving radially outward. In some cases, we are able to derive the azimuthal cross-section of the CME fronts, and we are able to measure the deviation from self-similar evolution. The results from this analysis show the importance of having multiple satellites dedicated to space weather forecasting, for example in orbits at the Lagrangian L4 and L5 points.