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Abstract
In situ measurements of coronal mass ejections (CMEs) when they pass over an interplanetary probe are one of the main ways we directly measure their properties. However, such in situ profiles are subject to several observational constraints that are still poorly understood. This work aims at quantifying one of them, namely, the aging effect, using a CME simulated with a three-dimensional magnetohydrodynamical code. The synthetic in situ profile and the instantaneous profile of the magnetic field strength differ more from each other when taken close to the Sun than far from it. Moreover, out of three properties we compute in this study (i.e., size, distortion parameter, and expansion speed), only the expansion speed shows a dependence of the aging as a function of distance. It is also the property that is the most impacted by the aging effect as it can amount to more than 100 km s−1 for CMEs observed closer than 0.15 au. This work calls for caution when deducing the expansion speed from CME profiles when they still are that close to the Sun since the aging effect can significantly impact the derived properties.
Department
Space Science Center
Publication Date
4-26-2024
Journal Title
The Astrophysical Journal Letters
Publisher
American Astronomical Society
Digital Object Identifier (DOI)
Document Type
Article
Recommended Citation
F. Regnault et al 2024 ApJL 966 L17
Rights
© 2024. The Author(s).
Comments
This is an open access article published by American Astronomical Society in The Astrophysical Journal Letters in 2024, available online: https://dx.doi.org/10.3847/2041-8213/ad3806