Abstract Details
| Name: SOUMYARANJAN KHUNTIA Affiliation: Indian Institute of Astrophysics Bangalore Conference ID: ASI2025_240 Title : Investigating the Thermodynamics of CMEs and Insights From the Successive CMEs Driving the 11 May 2024 Great Geomagnetic Storm Authors and Co-Authors : Soumyaranjan Khuntia 1, 2, Wageesh Mishra 1, Yuming Wang 3, Sudheer K Mishra 4, Jie Zhang 5, Shaoyu Lyu 3, Teresa Nieves-Chinchilla 6, Anjali Agarwal 1, 2 Abstract Type : Poster Abstract Category : Sun, Solar System, Exoplanets, and Astrobiology Abstract : Coronal mass ejections (CMEs) are gigantic expulsions of magnetized plasma from the Sun that significantly drive the space weather. While previous research has primarily focused on the kinematics of CMEs, more exploration of their thermodynamic evolution needs to be done. Our study presents a comprehensive analysis of the thermodynamic evolution of multiple fast and slow CMEs, including a detailed case study of the great geomagnetic storm on 11 May 2024. We have implemented the Flux Rope Internal State (FRIS) model to analyze distance-dependent variations in the polytropic index, heating rate, temperature, and internal forces of CMEs. The 3D kinematic data used as input for the FRIS model is derived from the Graduated Cylindrical Shell (GCS) model. Our findings indicate that fast CMEs release heat during their early stages of rapid deceleration and absorb heat during their near-constant acceleration phase. Slow CMEs, on contrast, exhibit mixed thermodynamic profiles--some undergoing heat absorption throughout their observed heights, while others display thermal behavior similar to fast CMEs. Our analysis reveals that although various CMEs show differential heating, they experience heat absorption at later propagation heights, approaching the near-isothermal state. Notably, CMEs with higher expansion speeds exhibit a less pronounced initial temperature drop before getting an isothermal state. Furthermore, the estimated 3D kinematics of responsible interplanetary CMEs (ICMEs) for the great 11 May 2024 storm case study suggest their en-route interaction, further confirmed by using in-situ measurements at 1 AU. Interestingly, for the case study, we note that electrons exhibit distinct thermal behaviors for pre and post-ICME (heat absorption) compared to those within the ICME (heat release), and ions show a bimodal thermal distribution inside the ICME. Our study highlights the importance of successive interacting CMEs towards the storm's severity and the need to understand their thermodynamic evolution better. |