Unraveling the untwisting process and upward mass transfer of a twisted prominence driven by vortex motion

Abstract

Solar filaments or prominences are common features in the Sun's atmosphere that contain cool chromospheric material suspended within the hot corona. However, the intricate topology of these structures and the mechanisms driving their instability and upward material transfer are not well understood. Investigating these issues is essential for gaining insight into the fundamental laws that govern solar activity. This study is to analyze a specific twisted prominence observed on February 10, 2021, and to explore its dynamics, including stability, motion, and material transfer. The study also aims to propose a mechanism, based on the K\'arm\'an Vortex Street instability, to explain the destabilization of the prominence. The study utilizes high-resolution H$_ alpha $ observations from the 1-m New Vacuum Solar Telescope and space-borne observations from the Solar Dynamics Observatory. These observations capture the characteristics and behavior of the twisted prominence. We analyzed the data to investigate the equilibrium state, subsequent destabilization, vortex motion, oscillations, resonations, untwisting, and upward mass loading of the prominence. We also detected and measured the speeds of outflows surrounding the prominence. The study reveals that the observed twisted prominence exhibited a stretched and twisted structure at its apex, distinguishing it from familiar cloudy prominences. Following a period of more than 30 hours in equilibrium, the prominence underwent destabilization, leading to a series of dynamic phenomena, such as vortex motion, oscillations, resonations, untwisting, and the upward transfer of mass. Consequently, material from the top of the prominence was carried upward and deposited into the overlying magnetic arcades. Noteworthy, outflows surrounding the prominence were characterized by speeds exceeding 40 km s$^ Based on these findings, we propose, for the first time, a mechanism rooted in the K\'arm\'an Vortex Street instability to explain the destabilization of the prominence. The estimated typical Strouhal Number of 0.23pm 0.06, which is related to vortex shedding, falls within the expected range for the K\'arm\'an Vortex Street effect, as predicted by simulations. These discoveries provide new insights into the dynamics and fundamental topology of solar prominences and reveal a previously unknown mechanism for mass loading into the upper atmosphere.