| Name: | Arjun Kannan |
| Affiliation: | IISER-Thiruvananthapuram |
| Conference ID : | ASI2024_23 |
| Title : | Investigating the Alfvénic nature of Vortex flows at different Magnetic configurations |
| Authors : | Arjun Kannan, Aswathi K, Nitin Yadav
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| Authors Affiliation: | 1 School of Physics, Indian Institute of Science Education and Research Thiruvananthapuram, Vithura, Thiruvananthapuram 695551, Kerala, India |
| Mode of Presentation: | Poster |
| Abstract Category : | Sun, Solar System, Exoplanets, and Astrobiology |
| Abstract : | Vortices or rotational plasma motions are omnipresent in turbulent flows, and the solar surface is no exception. Vortices are known to perturb magnetic flux footprints anchored at the solar surface and excite torsional Alfvén waves. These waves travel high in the atmosphere and potentially heat the plasma. Thus, investigating kinetic vortices and associated magnetic perturbations is essential to probe their role in the excitation of Alfvén waves. This study compares the distribution of vortices for three different magnetic regions, viz., Quiet Sun, Weak Plage and Strong Plage, using the realistic three-dimensional radiation-MHD code, MURaM. The Swirling Strength method is used to detect regions of vortex flows. The spatial scales of vortices at different heights, their origin at Intergranular lanes and the opposite sense of rotation between velocity and magnetic vortices are verified, which validates the Alfvénic nature of chromospheric vortices.
Using a simple flux tube expansion model and considering constant Alfvén energy flux indicates a much larger amplitude for velocity oscillation than detected in our simulations or reported in chromospheric solar observations. This discrepancy suggests that a physical mechanism transfers Alfvénic energy to other wave modes or heats the plasma. By examining power spectra of horizontal velocity at various layers, we conjecture that vortex interaction leads to energy transfer to smaller-scale vortices and contributes to chromospheric turbulence. It also results in the generation of swirling motions at chromospheric heights without any photospheric origin, as found in some recent studies.
Although photospheric kinetic vortices show similar properties in all magnetic configurations, the associated kinetic and magnetic vortices in the chromosphere are highly correlated for the Quiet Sun configuration compared to the Plage regions. These findings indicate the enhanced potential of Alfvén waves excitation through vortices in comparatively weaker magnetic regions. |
