Quantifying the toroidal flux of preexisting flux ropes of coronal mass ejections
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In past decades, much progress has been achieved in understanding the origin and evolution of coronal mass ejections (CMEs). In situ observations of the counterparts of CMEs, especially magnetic clouds (MCs) near the Earth, have provided measurements of the structure and total flux of CME flux ropes. However, it has been difficult to measure these properties in an erupting CME flux rope, in particular in a preexisting flux rope. In this work, we propose a model to estimate the toroidal flux of a preexisting flux rope by subtracting the flux contributed by magnetic reconnection during the eruption from the flux measured in the MC. The flux contributed by the reconnection is derived from geometric properties of two-ribbon flares based on a quasi-2D reconnection model. We then apply the model to four CME/flare events and find that the ratio of toroidal flux in the preexisting flux rope to that in the associated MC lies in the range 0.40–0.88. This indicates that the toroidal flux of the preexisting flux rope makes an important contribution to that of the CME flux rope and is usually at least as large as the flux arising from the eruption process for the selected events.
Xing , C , Cheng , X , Qiu , J , Hu , Q , Priest , E R & Ding , M D 2020 , ' Quantifying the toroidal flux of preexisting flux ropes of coronal mass ejections ' , Astrophysical Journal , vol. 889 , no. 2 , 125 . https://doi.org/10.3847/1538-4357/ab6321
Copyright © 2020. The American Astronomical Society. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s )and the title of the work, journal citation and DOI.
DescriptionFunding: SOHO is a project of international cooperation between ESA and NASA. C.X., X.C. and M.D.D. are funded by NSFC grants 11722325, 11733003, 11790303, 11790300, Jiangsu NSF grants BK20170011, and "Dengfeng B" program of Nanjing University.
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