| Name: | Soumyaranjan Khuntia |
| Affiliation: | Indian Institute of Astrophysics Bengaluru |
| Conference ID : | ASI2024_82 |
| Title : | Modeling the Thermodynamic Enigma of CMEs During Their Propagation |
| Authors : | Soumyaranjan Khuntia1,2, Wageesh Mishra1, Sudheer K Mishra1,3, Yuming Wang4, Jie Zhang 5 and Shaoyu Lyu4 |
| Authors Affiliation: | 1 Indian Institute of Astrophysics, II Block, Koramangala, Bengaluru 560034, India
2 Pondicherry University, R.V. Nagar, Kalapet 605014, Puducherry, India
3 Astronomical Observatory, Kyoto University, Sakyo, Kyoto 606-8502, Japan
4 CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei 230026, People’s Republic of China
5 Department of Physics and Astronomy, George Mason University, 4400 University Dr., MSN 3F3, Fairfax, VA 22030, USA |
| Mode of Presentation: | Poster |
| Abstract Category : | Sun, Solar System, Exoplanets, and Astrobiology |
| Abstract : | Coronal Mass Ejections (CMEs) are ejections of magnetized plasma from the Sun, posing potential threats to space weather. Extensive research has focused on the kinematics of CMEs; however, the thermodynamic properties are explored in a handful of studies, limited to specific heliocentric distances closer to the Sun. Our study delves into the diverse kinematic profiles and related thermodynamic evolution of both a fast CME (CME1) and a slow CME (CME2) at coronal heights where thermodynamic measurements have been challenging. We estimated distance-dependent evolution in various internal parameters using the improved Flux Rope Internal State (FRIS) model. The model incorporates inputs of 3D kinematics obtained from the GCS model. Our findings reveal that CMEs can maintain their temperature above the adiabatic cooling threshold despite their expansion and during later propagation phases, ultimately approaching an isothermal state. Notably, the faster CME1 attains an adiabatic state followed by an isothermal state closer to the Sun than the slower CME2. Multi-wavelength observations of flux-ropes at source regions support the FRIS model-derived findings at initially observed lower coronal heights. Furthermore, our investigation on multiple fast CMEs demonstrates that Faster CMEs maintaining higher expansion speeds exhibit less pronounced temperature decreases. Our analysis elucidates the dominant factors influencing CME radial expansion, with centrifugal and thermal pressure forces playing pivotal roles, while the Lorentz force acts as a constraining factor. Notably, the thermal pressure force governs expansion at higher heights and is solely responsible for radial expansion. This study enriches our understanding of the internal properties of CMEs, offering valuable insights for refining assumptions in the polytropic index value for better CME property projections.
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