Barczynski, K., Schmieder, B., Peat, A. W., Labrosse, N. , Mein, P. and Mein, N. (2022) Spectro-imagery of an active tornado-like prominence: Formation and evolution. Astronomy and Astrophysics, 653, A94. (doi: 10.1051/0004-6361/202140976)
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Abstract
Context. The dynamical nature of fine structures in prominences remains an open issue, including rotating flows in tornado prominences. While the Atmospheric Imaging Assembly imager aboard the Solar Dynamics Observatory allowed us to follow the global structure of a tornado-like prominence for five hours, the Interface Region Imaging Spectrograph, and the Multichannel Subtractive Double Pass spectrograph permitted to obtain plasma diagnostics of its fine structures. Aims. We aim to address two questions. Firstly, is the observed plasma rotation conceptually acceptable in a flux rope magnetic support configuration with dips? Secondly, how is the plasma density distributed in the tornado-like prominence? Methods. We calculated line-of-sight velocities and non-thermal line widths using Gaussian fitting for Mg II lines and the bisector method for Hα line. We determined the electron density from Mg II line integrated intensities and profile fitting methods using 1D non-LTE radiative transfer theory models. Results. The global structure of the prominence observed in Hα, and Mg II h, and k line fits with a magnetic field structure configuration with dips. Coherent Doppler shifts in redshifted and blueshifted areas observed in both lines were detected along rapidly-changing vertical and horizontal structures. However, the tornado at the top of the prominence consists of multiple fine threads with opposite flows, suggesting counter-streaming flows rather than rotation. Surprisingly we found that the electron density at the top of the prominence could be larger (1011 cm−3) than in the inner part of the prominence. Conclusions. We suggest that the tornado is in a formation state with cooling of hot plasma in a first phase, and following that, a phase of leakage of the formed blobs with large transverse flows of material along long loops extended away from the UV prominence top. The existence of such long magnetic field lines on both sides of the prominence would stop the tornado-like prominence from really turning around its axis.
| Item Type: | Articles |
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| Additional Information: | This study benefited from financial support from the Programme National Soleil Terre (PNST) of the CNRS/INSU, as well as from the Programme des Investissements d’Avenir (PIA) supervised by the Agence nationale de la recherche. The work of KB is funded by the LabEx Plas@Par which is driven by Sorbonne Université. AWP acknowledges financial support from the Science and Technology Facilities Council (STFC) via grant ST/S505390/1. NL acknowledges support from STFC grants ST/P000533/1 and ST/T000422/1. |
| Status: | Published |
| Refereed: | Yes |
| Glasgow Author(s) Enlighten ID: | Labrosse, Dr Nicolas and Peat, Dr Aaron and Schmieder, Prof Brigitte |
| Authors: | Barczynski, K., Schmieder, B., Peat, A. W., Labrosse, N., Mein, P., and Mein, N. |
| College/School: | College of Science and Engineering > School of Physics and Astronomy |
| Journal Name: | Astronomy and Astrophysics |
| Publisher: | EDP Sciences |
| ISSN: | 0004-6361 |
| ISSN (Online): | 1432-0746 |
| Published Online: | 15 September 2021 |
| Copyright Holders: | Copyright © ESO 2021 |
| First Published: | First published in Astronomy and Astrophysics 653: A94 |
| Publisher Policy: | Reproduced in accordance with the publisher copyright policy |
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