Active-Region Twist Derived from Magnetic Tongues and Linear Force-Free Extrapolations

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The main aim of this study is to compare the amount of twist present in emerging active regions (ARs) from photospheric and coronal data. We use linear force-free field models of the observed coronal structure of ARs to determine the global twist. The coronal twist is derived, on one hand, from the...

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Autores principales: Poisson, M., López Fuentes, M., Mandrini, C.H., Démoulin, P.
Formato: JOUR
Materias:
Active regions: magnetic fields
Active regions: structure
Corona: models
Helicity: magnetic
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00380938_v290_n11_p3279_Poisson
Aporte de:
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id todo:paper_00380938_v290_n11_p3279_Poisson
record_format dspace
spelling todo:paper_00380938_v290_n11_p3279_Poisson2023-10-03T14:48:51Z Active-Region Twist Derived from Magnetic Tongues and Linear Force-Free Extrapolations Poisson, M. López Fuentes, M. Mandrini, C.H. Démoulin, P. Active regions: magnetic fields Active regions: structure Corona: models Helicity: magnetic The main aim of this study is to compare the amount of twist present in emerging active regions (ARs) from photospheric and coronal data. We use linear force-free field models of the observed coronal structure of ARs to determine the global twist. The coronal twist is derived, on one hand, from the force-free parameter [α] of the model and, on the other, from the computed coronal magnetic helicity normalized by the magnetic flux squared. We compare our results, for the same set of ARs, with those of Poisson et al. (Solar Phys.290, 727, 2015), in which the twist was estimated using the so-called magnetic tongues observed in line-of-sight magnetograms during AR emergence. We corroborate the agreement between the photospheric and coronal twist-sign and the presence of magnetic tongues as an early proxy of the AR non-potentiality. We find a globally linear relationship between the coronal twist and the one previously deduced for the emerging AR flux rope at the photospheric level. The coronal-twist value is typically lower by a factor of six than the one deduced for the emerging flux rope. We interpret this result as due to the partial emergence of the flux rope that forms the region. © 2015, Springer Science+Business Media Dordrecht. Fil:Poisson, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:López Fuentes, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00380938_v290_n11_p3279_Poisson
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Active regions: magnetic fields
Active regions: structure
Corona: models
Helicity: magnetic
spellingShingle Active regions: magnetic fields
Active regions: structure
Corona: models
Helicity: magnetic
Poisson, M.
López Fuentes, M.
Mandrini, C.H.
Démoulin, P.
Active-Region Twist Derived from Magnetic Tongues and Linear Force-Free Extrapolations
topic_facet Active regions: magnetic fields
Active regions: structure
Corona: models
Helicity: magnetic
description The main aim of this study is to compare the amount of twist present in emerging active regions (ARs) from photospheric and coronal data. We use linear force-free field models of the observed coronal structure of ARs to determine the global twist. The coronal twist is derived, on one hand, from the force-free parameter [α] of the model and, on the other, from the computed coronal magnetic helicity normalized by the magnetic flux squared. We compare our results, for the same set of ARs, with those of Poisson et al. (Solar Phys.290, 727, 2015), in which the twist was estimated using the so-called magnetic tongues observed in line-of-sight magnetograms during AR emergence. We corroborate the agreement between the photospheric and coronal twist-sign and the presence of magnetic tongues as an early proxy of the AR non-potentiality. We find a globally linear relationship between the coronal twist and the one previously deduced for the emerging AR flux rope at the photospheric level. The coronal-twist value is typically lower by a factor of six than the one deduced for the emerging flux rope. We interpret this result as due to the partial emergence of the flux rope that forms the region. © 2015, Springer Science+Business Media Dordrecht.
format JOUR
author Poisson, M.
López Fuentes, M.
Mandrini, C.H.
Démoulin, P.
author_facet Poisson, M.
López Fuentes, M.
Mandrini, C.H.
Démoulin, P.
author_sort Poisson, M.
title Active-Region Twist Derived from Magnetic Tongues and Linear Force-Free Extrapolations
title_short Active-Region Twist Derived from Magnetic Tongues and Linear Force-Free Extrapolations
title_full Active-Region Twist Derived from Magnetic Tongues and Linear Force-Free Extrapolations
title_fullStr Active-Region Twist Derived from Magnetic Tongues and Linear Force-Free Extrapolations
title_full_unstemmed Active-Region Twist Derived from Magnetic Tongues and Linear Force-Free Extrapolations
title_sort active-region twist derived from magnetic tongues and linear force-free extrapolations
url http://hdl.handle.net/20.500.12110/paper_00380938_v290_n11_p3279_Poisson
work_keys_str_mv AT poissonm activeregiontwistderivedfrommagnetictonguesandlinearforcefreeextrapolations
AT lopezfuentesm activeregiontwistderivedfrommagnetictonguesandlinearforcefreeextrapolations
AT mandrinich activeregiontwistderivedfrommagnetictonguesandlinearforcefreeextrapolations
AT demoulinp activeregiontwistderivedfrommagnetictonguesandlinearforcefreeextrapolations
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