Polarimetric measurements in prominences and “tornadoes” observed by THEMIS

Schmieder, B., Ariste, A. L., Levens, P., Labrosse, N. and Dalmasse, K. (2014) Polarimetric measurements in prominences and “tornadoes” observed by THEMIS. Proceedings of the International Astronomical Union, 10(S305), pp. 275-281. (doi:10.1017/S1743921315004895)

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Abstract

Since 2013, coordinated campaigns with the THEMIS spectropolarimeter in Tenerife and other instruments (space based: Hinode/SOT, IRIS or ground based: Sac Peak, Meudon) are organized to observe prominences. THEMIS records spectropolarimetry at the He I D3 and we use the PCA inversion technique to derive their field strength, inclination and azimuth. All of the observed prominences are quiescent, as they were stable as filaments for at least three days and not eruptive. They present similar characteristics, they are highly dynamic and present horizontal magnetic fields. Statistically, the inclination from the local vertical is around 90 degrees, with some points around 60 and 120 degrees. The field strength is between 5 and 15 Gauss. We tested the effects of adding a turbulent field component to the horizontal field. For those pixels showing inclinations around 60 and 120 degrees, we find that such a model is compatible with the polarimetric observations. In some of these prominences, identified as “tornadoes” the field strength may reach 50 Gauss, and in the top of the tornadoes some points exhibit an inclination which cannot correspond to any model in our grid of models. We investigate different solutions.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Labrosse, Dr Nicolas and Levens, Peter
Authors: Schmieder, B., Ariste, A. L., Levens, P., Labrosse, N., and Dalmasse, K.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Proceedings of the International Astronomical Union
Publisher:Cambridge University Press
ISSN:1743-9213
ISSN (Online):1743-9221
Copyright Holders:Copyright © 2014 Cambridge University Press
First Published:First published in Proceedings of the International Astronomical Union 10(S305):275-281
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher.

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