Kinematics and Thermodynamics of Coronal Mass Ejections
Abstract
Coronal mass ejections (CMEs) are major drivers of space weather, yet their thermodynamic evolution remains insufficiently constrained. This thesis develops a comprehensive framework linking CME kinematics, thermodynamics, internal force balance, and geoeffectiveness through analytical modelling and multi-viewpoint observations. The developed FRIS model uses observed kinematics to infer otherwise inaccessible internal plasma properties, including the polytropic index. A systematic investigation of fast CMEs reveals an initial heat-release phase followed by a transition towards near-isothermal evolution, typically around 3-9 solar radii. The evolving contributions of thermal-pressure and centrifugal forces, opposed by the Lorentz force, establish a connection between expansion and thermal evolution. The findings demonstrate the limitations of assuming a fixed polytropic index in magnetohydrodynamic models of CME propagation. At 1 au, in situ observations reveal persistent non-adiabatic evolution, accompanied by turbulence and localised intermittency. The interacting CMEs associated with the May 2024 great storm show restructured magnetic and thermal configurations, producing double-flux-rope-like signatures and species-dependent heating, with electron thermodynamics as a better indicator of recent interactions. Statistical analysis of nearly 600 ME demonstrates that 45% exhibit net heating with a solar cycle dependence. Notably, High-impact ejecta preferentially exhibit stronger heating signatures, establishing thermal state as a complementary diagnostic of geoeffectiveness. Overall, this thesis establishes CMEs as intrinsically non-adiabatic systems whose thermodynamic evolution is coupled to expansion, internal force balance, solar-cycle variability, and CME-CME interactions, with important implications for understanding geoeffectiveness and improving space-weather assessment.
Related
- Influence of local and global solar magnetic fields on medium-term forecasting of the number and parameters of coronal mass ejections
- Coronal Mass Ejections from Young Suns: An Observational View through the Solar-Stellar Connection
- A Global Magnetohydrodynamic Simulation of the Birth and Cannibalism of Homologous Coronal Mass Ejections
- A Global Magnetohydrodynamic Simulation of the Birth and Cannibalism of Homologous Coronal Mass Ejections
- Fallback-triggered Reconnection Drives Coronal Mass Ejections on II Pegasi
BibTeX
@misc{khuntia2026kinematics,
title = {{Kinematics and Thermodynamics of Coronal Mass Ejections}},
author = {Soumyaranjan Khuntia},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.26219},
eprint = {2610.26219},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.26219},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Kinematics and Thermodynamics of Coronal Mass Ejections
AU - Soumyaranjan Khuntia
PY - 2026
DA - 2026/10/19
PB - arXiv
DO - 10.48550/arxiv.2610.26219
UR - https://arxiv.org/abs/2610.26219
AB - Coronal mass ejections (CMEs) are major drivers of space weather, yet their thermodynamic evolution remains insufficiently constrained. This thesis develops a comprehensive framework linking CME kinematics, thermodynamics, internal force balance, and geoeffectiveness through analytical modelling and multi-viewpoint observations. The developed FRIS model uses observed kinematics to infer otherwise inaccessible internal plasma properties, including the polytropic index. A systematic investigation of fast CMEs reveals an initial heat-release phase followed by a transition towards near-isothermal evolution, typically around 3-9 solar radii. The evolving contributions of thermal-pressure and centrifugal forces, opposed by the Lorentz force, establish a connection between expansion and thermal evolution. The findings demonstrate the limitations of assuming a fixed polytropic index in magnetohydrodynamic models of CME propagation. At 1 au, in situ observations reveal persistent non-adiabatic evolution, accompanied by turbulence and localised intermittency. The interacting CMEs associated with the May 2024 great storm show restructured magnetic and thermal configurations, producing double-flux-rope-like signatures and species-dependent heating, with electron thermodynamics as a better indicator of recent interactions. Statistical analysis of nearly 600 ME demonstrates that 45% exhibit net heating with a solar cycle dependence. Notably, High-impact ejecta preferentially exhibit stronger heating signatures, establishing thermal state as a complementary diagnostic of geoeffectiveness. Overall, this thesis establishes CMEs as intrinsically non-adiabatic systems whose thermodynamic evolution is coupled to expansion, internal force balance, solar-cycle variability, and CME-CME interactions, with important implications for understanding geoeffectiveness and improving space-weather assessment.
ER -