Issue |
A&A
Volume 684, April 2024
|
|
---|---|---|
Article Number | A154 | |
Number of page(s) | 5 | |
Section | The Sun and the Heliosphere | |
DOI | https://doi.org/10.1051/0004-6361/202347786 | |
Published online | 17 April 2024 |
Horizontally polarized kink oscillations supported by solar coronal loops in an asymmetric environment⋆
1
Shandong Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Institute of Space Sciences, Shandong University, Weihai, Shandong 264209, PR China
e-mail: shimijie@sdu.edu.cn
2
Institute of Frontier and Interdisciplinary Science, Shandong University, Qingdao, Shandong 266237, PR China
Received:
23
August
2023
Accepted:
15
February
2024
Context. Kink oscillations are ubiquitously observed in solar coronal loops, and understanding them is crucial in the contexts of coronal seismology and atmospheric heating.
Aims. We studied kink modes supported by a straight coronal loop embedded in an asymmetric environment using 3D magnetohydrodynamic simulations.
Methods. We implemented the asymmetric effect by setting different exterior densities below and above the loop interior and initiated the simulation using a kink-like velocity perturbation perpendicular to the loop plane, mimicking the frequently measured horizontally polarized kink modes.
Results. We find that the external velocity fields show fan-blade structures propagating in the azimuthal direction as a result of the successive excitation of higher azimuthal Fourier modes. Resonant absorption and phase-mixing can still occur despite an asymmetric environment, leading to the development of small-scale structures at loop boundaries. These small-scale structures nonetheless develop asymmetrically at the upper and lower boundaries due to the different gradients of the Alfvén speed.
Conclusions. These findings enrich our understanding of kink modes in coronal loops embedded within an asymmetric environment, providing insights that will be helpful for future high-resolution observations.
Key words: Sun: corona / Sun: oscillations
Movie associated to Fig. 3 is available at https://www.aanda.org
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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