Evidence for Vortex Shedding in the Sun's Hot Corona

Abstract

Vortex shedding is an oscillating flow that is commonly observed in fluids due to the presence of a blunt body in a flowing medium. Numerical simulations have shown that the phenomenon of vortex shedding could also develop in the magnetohydrodynamic (MHD) domain. The dimensionless Strouhal number, the ratio of the blunt body diameter to the product of the period of vortex shedding and the speed of a flowing medium, is a robust indicator for vortex shedding, and, generally of the order of 0.2 for a wide range of Reynolds number. Using an observation from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, we report a wavelike or oscillating plasma flow propagating upward against the Sun's gravitational force. A newly formed shrinking loop in the post-flare region possibly generates the oscillation of the upflow in the wake of the hot and dense loop through vortex shedding. The computed Strouhal number is consistent with the prediction from previous MHD simulations. Our observation suggests the possibility of vortex shedding in the solar corona.

6 pages, Published in PRL, Ref: T. Samanta, H. Tian, and V. M. Nakariakov, Phys. Rev. Lett. 123, 035102 (2019)

References in corpus (5)

• The Kelvin-Helmholtz Instability at CME-Boundaries in the Solar Corona: Observations and 2.5D MHD Simulations
• Kelvin-Helmholtz instability in solar chromospheric jets: theory and observation
• An exploration of heating mechanisms in a supra-arcade plasma sheet formed after a coronal mass ejection
• Secondary Rayleigh-Taylor type Instabilities in the Reconnection Exhaust Jet as a Mechanism for Supra-Arcade Downflows
• Thermodynamics of supra-arcade downflows in solar flares