TY - JOUR
T1 - Transverse Loop Oscillations via Vortex Shedding
T2 - A Self-oscillating Process
AU - Karampelas, Konstantinos
AU - Van Doorsselaere, Tom
N1 - Funding information: The authors would like to thank the referee for helpful
comments. 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.
PY - 2021/2/10
Y1 - 2021/2/10
N2 - 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.
AB - 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.
U2 - 10.3847/2041-8213/abdc2b
DO - 10.3847/2041-8213/abdc2b
M3 - Article
SN - 2041-8205
VL - 908
SP - 1
EP - 7
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L7
ER -