Exploring the Thermodynamic Evolution of CMEs: An Analytical Modeling Approach Using Global Kinematics

Soumyaranjan Khuntia

Hosted by Indian Institute of Astrophysics (IIA), India on February 22, 2024


Coronal Mass Ejections (CMEs), sporadic eruptions of magnetized plasma from the Sun, present a significant concern for society’s reliance on space-based infrastructure. Our study uniquely delves into the evolution of thermodynamic properties of CMEs, a facet often less understood due to both remote and in-situ observational limitations. This seminar will briefly discuss the used analytical model (FRIS: Flux Rope Internal State) and the model-derived distance-dependent evolution of various internal parameters at coronal heights where thermodynamic measurements have been challenging. Our findings reveal that CMEs can maintain temperatures above the adiabatic cooling threshold, approaching an isothermal state during later propagation phases. Notably, the faster CME achieves an adiabatic state followed by an isothermal state closer to the Sun than the slower one. Furthermore, exploring multiple fast CMEs unveils that those maintaining higher expansion speeds experience more modest declines in temperature. The multi-wavelength observations of CME-associated flux-ropes at source regions support the modelderived findings at lower coronal heights. Our analysis also highlights the dominant forces influencing CME radial expansion, with centrifugal and thermal pressure forces playing pivotal roles, while the Lorentz force acts as a constraining factor. Intriguingly, the thermal pressure force emerges as the sole driver of radial expansion at higher heights. This study provides valuable insights for refining assumptions on the polytropic index value to forecast CME characteristics better.


Wageesh Mishra (IIA, India) , Sudheer K Mishra (Kyoto University, Japan) , Yuming Wang (University of Science and Technology of China) , Jie Zhang (George Mason University, USA) , Teresa Nieves-Chinchilla (NASA Goddard Space Flight Center, USA), and Shaoyu Lyu (University of Science and Technology of China)

Recorded video