Magnetic tornadoes and chromospheric swirls -- Definition and classification

Abstract

Chromospheric swirls are the observational signatures of rotating magnetic field structures in the solar atmosphere, also known as magnetic tornadoes. Swirls appear as dark rotating features in the core of the spectral line of singly ionized calcium at a wavelength of 854.2 nm. This signature can be very subtle and difficult to detect given the dynamic changes in the solar chromosphere. Important steps towards a systematic and objective detection method are the compilation and characterization of a statistically significant sample of observed and simulated chromospheric swirls. Here, we provide a more exact definition of the chromospheric swirl phenomenon and also present a first morphological classification of swirls with three types: (I) Ring, (II) Split, (III) Spiral. We also discuss the nature of the magnetic field structures connected to tornadoes and the influence of limited spatial resolution on the appearance of their photospheric footpoints.

8 pages, 4 figures, proceedings article for the conference "Eclipse on the Coral Sea: Cycle 24 Ascending" GONG 2012/LWS/SDO-5/SOHO 27, which has been held in Palm Cove, Australia, in 2012. Accepted version

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• The formation and disintegration of magnetic bright points observed by Sunrise/IMaX
• First simultaneous SST/CRISP and IRIS observations of a small-scale quiet Sun vortex
• Automated Swirl Detection Algorithm (ASDA) and Its Application to Simulation and Observational Data
• Stirring the Base of the Solar Wind: On Heat Transfer and Vortex Formation
• Magnetic swirls and associated fast magnetoacoustic kink waves in a solar chromospheric flux tube
• Vortices evolution in the solar atmosphere: A dynamical equation for the swirling strength
• Magnetic Tornado Properties: A Substantial Contribution to the Solar Coronal Heating via Efficient Energy Transfer
• Photospheric Logarithmic Velocity Spirals as MHD Wave Generation Mechanisms
• Large-Scale Vortex Motion and Multiple Plasmoid Ejection Due to Twisting Prominence Threads and Associated Reconnection
• High mode magnetohydrodynamic waves propagation in a twisted rotating jet emerging from a filament eruption