Comparing UV/EUV line parameters and magnetic field in a quiescent prominence with tornadoes

Levens, P.J., Labrosse, N. , Schmieder, B., López Ariste, A. and Fletcher, L. (2017) Comparing UV/EUV line parameters and magnetic field in a quiescent prominence with tornadoes. Astronomy and Astrophysics, 607, A16. (doi:10.1051/0004-6361/201730808)

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Abstract

Context. Understanding the relationship between plasma and the magnetic field is important for describing and explaining the observed dynamics of solar prominences. Aims. We determine if a close relationship can be found between plasma and magnetic field parameters, measured at high resolution in a well-observed prominence. Methods. A prominence observed on 15 July 2014 by the Interface Region Imaging Spectrograph (IRIS), Hinode, the Solar Dynamics Observatory (SDO), and the Télescope Héliographique pour l’Etude du Magnétisme et des Instabilités Solaires (THEMIS) is selected. We perform a robust co-alignment of data sets using a 2D cross-correlation technique. Magnetic field parameters are derived from spectropolarimetric measurements of the He i D3 line from THEMIS. Line ratios and line-of-sight velocities from the Mg ii h and k lines observed by IRIS are compared with magnetic field strength, inclination, and azimuth. Electron densities are calculated using Fe xii line ratios from the Hinode Extreme-ultraviolet Imaging Spectrometer, which are compared to THEMIS and IRIS data. Results. We find Mg ii k/h ratios of around 1.4 everywhere, similar to values found previously in prominences. Also, the magnetic field is strongest (∼ 30 G) and predominantly horizontal in the tornado-like legs of the prominence. The k3 Doppler shift is found to be between ± 10 km s−1 everywhere. Electron densities at a temperature of 1.5 × 106 K are found to be around 109 cm−3 . No significant correlations are found between the magnetic field parameters and any of the other plasma parameters inferred from spectroscopy, which may be explained by the large differences in the temperatures of the lines used in this study. Conclusions. This is the first time that a detailed statistical study of plasma and magnetic field parameters has been performed at high spatial resolution in a prominence. Our results provide important constraints on future models of the plasma and magnetic field in these structures.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Levens, Peter and Fletcher, Professor Lyndsay and Labrosse, Dr Nicolas
Authors: Levens, P.J., Labrosse, N., Schmieder, B., López Ariste, A., and Fletcher, L.
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:01 September 2017
Copyright Holders:Copyright © 2017 EDP Sciences
First Published:First published in Astronomy and Astrophysics 607: A16
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
619541STFC Doctoral Training Grant 2012-17Martin HendryScience & Technology Facilities Council (STFC)ST/K502005/1S&E P&A - PHYSICS & ASTRONOMY
631581Consolidated grant in solar and astrophysical plasmasLyndsay FletcherScience & Technology Facilities Council (STFC)ST/L000741/1S&E P&A - PHYSICS & ASTRONOMY