A study of the kinematic and volumetric co-evolution of Earth-directed CMEs

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Main Authors: Pattnaik, Ashutosh, Gopalswamy, Nat, Sarkar, Ranadeep, Xie, Hong, Akiyama, Sachiko, Michalek, Grzegorz
Format: Preprint
Published: 2026
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author Pattnaik, Ashutosh
Gopalswamy, Nat
Sarkar, Ranadeep
Xie, Hong
Akiyama, Sachiko
Michalek, Grzegorz
author_facet Pattnaik, Ashutosh
Gopalswamy, Nat
Sarkar, Ranadeep
Xie, Hong
Akiyama, Sachiko
Michalek, Grzegorz
contents While flare-associated CMEs generally show a strong association between flare X-ray flux and CME kinematics, their volumetric evolution and its link to both kinematics and flare activity remains less explored. In this study, we investigate the volumetric and kinematic co-evolution of ten Earth-directed, flare-associated CMEs using multi-viewpoint observations from STEREO-A, STEREO-B, and SOHO. We perform 3D reconstructions of the CME flux ropes with the Graduated Cylindrical Shell (GCS) model and derive their geometrical parameters. We find that the total CME volume follows a power-law dependence on the leading edge height, and that different structural components expand at different rates, with the ellipsoidal front expanding faster than the conical legs. Furthermore, the volumetric evolution follows a multi-phase pattern: initial overexpansion, a gradual reduction in the expansion rate, and finally saturation at a higher heliocentric distance. This is similar to the well-established three-phase evolution of the CME kinematics. Notably, the second-order derivative of volume with time shows a strong temporal correlation with both CME acceleration and the GOES soft X-ray flux of the associated flare. This is the first study to report such a correspondence between volumetric evolution and flare timing, highlighting the role of flare energy release in governing CME expansion dynamics. Our findings motivate further studies into the coupling between magnetic reconnection and CME volumetric evolution in the corona.
format Preprint
id arxiv_https___arxiv_org_abs_2605_02828
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A study of the kinematic and volumetric co-evolution of Earth-directed CMEs
Pattnaik, Ashutosh
Gopalswamy, Nat
Sarkar, Ranadeep
Xie, Hong
Akiyama, Sachiko
Michalek, Grzegorz
Solar and Stellar Astrophysics
While flare-associated CMEs generally show a strong association between flare X-ray flux and CME kinematics, their volumetric evolution and its link to both kinematics and flare activity remains less explored. In this study, we investigate the volumetric and kinematic co-evolution of ten Earth-directed, flare-associated CMEs using multi-viewpoint observations from STEREO-A, STEREO-B, and SOHO. We perform 3D reconstructions of the CME flux ropes with the Graduated Cylindrical Shell (GCS) model and derive their geometrical parameters. We find that the total CME volume follows a power-law dependence on the leading edge height, and that different structural components expand at different rates, with the ellipsoidal front expanding faster than the conical legs. Furthermore, the volumetric evolution follows a multi-phase pattern: initial overexpansion, a gradual reduction in the expansion rate, and finally saturation at a higher heliocentric distance. This is similar to the well-established three-phase evolution of the CME kinematics. Notably, the second-order derivative of volume with time shows a strong temporal correlation with both CME acceleration and the GOES soft X-ray flux of the associated flare. This is the first study to report such a correspondence between volumetric evolution and flare timing, highlighting the role of flare energy release in governing CME expansion dynamics. Our findings motivate further studies into the coupling between magnetic reconnection and CME volumetric evolution in the corona.
title A study of the kinematic and volumetric co-evolution of Earth-directed CMEs
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2605.02828