Transverse Loop Oscillations via Vortex Shedding: A Self-oscillating Process

Karampelas, Konstantinos and Van Doorsselaere, Tom (2021) Transverse Loop Oscillations via Vortex Shedding: A Self-oscillating Process. Astrophysical Journal Letters, 908 (1). L7. ISSN 2041-8213

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Official URL: https://doi.org/10.3847/2041-8213/abdc2b

Abstract

Identifying the underlying mechanisms behind the excitation of transverse oscillations in coronal loops is essential for their role as diagnostic tools in coronal seismology and their potential use as wave heating mechanisms of the solar corona. In this paper, we explore the concept of these transverse oscillations being excited through a self-sustaining process, caused by Alfvénic vortex shedding from strong background flows interacting with coronal loops. We show for the first time in 3D simulations that vortex shedding can generate transverse oscillations in coronal loops, in the direction perpendicular to the flow due to periodic "pushing" by the vortices. By plotting the power spectral density we identify the excited frequencies of these oscillations. We see that these frequencies are dependent both on the speed of the flow, as well as the characteristics of the oscillating loop. This, in addition to the fact that the background flow is constant and not periodic, makes us treat this as a self-oscillating process. Finally, the amplitudes of the excited oscillations are near constant in amplitude, and are comparable with the observations of decay-less oscillations. This makes the mechanism under consideration a possible interpretation of these undamped waves in coronal loops.

Item Type: Article
Additional Information: Funding information: K.K. has received support for this study through a postdoctoral mandate from KU Leuven Internal Funds (PDM/2019), by a UK Science and Technology Facilities Council (STFC) grant ST/T000384/1, and by a FWO (Fonds voor Wetenschappelijk OnderzoekVlaanderen) postdoctoral fellowship (1273221N). T.V.D. is supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No. 724326) and the C1 grant TRACESpace of Internal Funds KU Leuven. The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Research Foundation Flanders (FWO) and the Flemish Government–department EWI.
Subjects: F300 Physics
F500 Astronomy
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Related URLs:
Depositing User: Elena Carlaw
Date Deposited: 30 Jun 2021 15:53
Last Modified: 30 Jun 2021 16:00
URI: http://nrl.northumbria.ac.uk/id/eprint/46569

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