Decametric N burst: A consequence of the interaction of two coronal mass ejections

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Radio emissions of electron beams in the solar corona and interplanetary space are tracers of the underlying magnetic configuration and of its evolution. We analyse radio observations from the Culgoora and WIND/WAVES spectrographs, in combination with SOHO/LASCO and SOHO/MDI data, to understand the...

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Autores principales: Démoulin, P., Klein, K.-L., Goff, C.P., Van Driel-Gesztelyi, L., Culhane, J.L., Mandrini, C.H., Matthews, S.A., Harra, L.K.
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Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00380938_v240_n2_p301_Demoulin
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_00380938_v240_n2_p301_Demoulin2023-10-03T14:48:37Z Decametric N burst: A consequence of the interaction of two coronal mass ejections Démoulin, P. Klein, K.-L. Goff, C.P. Van Driel-Gesztelyi, L. Culhane, J.L. Mandrini, C.H. Matthews, S.A. Harra, L.K. Radio emissions of electron beams in the solar corona and interplanetary space are tracers of the underlying magnetic configuration and of its evolution. We analyse radio observations from the Culgoora and WIND/WAVES spectrographs, in combination with SOHO/LASCO and SOHO/MDI data, to understand the origin of a type N burst originating from NOAA AR 10540 on January 20, 2004, and its relationship with type II and type III emissions. All bursts are related to the flares and the CME analysed in a previous paper (Goff et al., 2007). A very unusual feature of this event was a decametric type N burst, where a type III-like burst, drifting towards low frequencies (negative drift), changes drift first to positive, then again to negative. At metre wavelengths, i.e., heliocentric distances ≲1.5R ⊙, these bursts are ascribed to electron beams bouncing in a closed loop. Neither U nor N bursts are expected at decametric wavelengths because closed quasi-static loops are not thought to extend to distances ≫1.5R ⊙. We take the opportunity of the good multi-instrument coverage of this event to analyse the origin of type N bursts in the high corona. Reconnection of the expanding ejecta with the magnetic structure of a previous CME, launched about 8 hours earlier, injects electrons in the same manner as with type III bursts but into open field lines having a local dip and apex. The latter shape was created by magnetic reconnection between the expanding CME and neighbouring (open) streamer field lines. This particular flux tube shape in the high corona, between 5R ⊙ and 10R ⊙, explains the observed type N burst. Since the required magnetic configuration is only a transient phenomenon formed by reconnection, severe timing and topological constraints are present to form the observed decametric N burst. They are therefore expected to be rare features. © Springer 2007. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00380938_v240_n2_p301_Demoulin
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description Radio emissions of electron beams in the solar corona and interplanetary space are tracers of the underlying magnetic configuration and of its evolution. We analyse radio observations from the Culgoora and WIND/WAVES spectrographs, in combination with SOHO/LASCO and SOHO/MDI data, to understand the origin of a type N burst originating from NOAA AR 10540 on January 20, 2004, and its relationship with type II and type III emissions. All bursts are related to the flares and the CME analysed in a previous paper (Goff et al., 2007). A very unusual feature of this event was a decametric type N burst, where a type III-like burst, drifting towards low frequencies (negative drift), changes drift first to positive, then again to negative. At metre wavelengths, i.e., heliocentric distances ≲1.5R ⊙, these bursts are ascribed to electron beams bouncing in a closed loop. Neither U nor N bursts are expected at decametric wavelengths because closed quasi-static loops are not thought to extend to distances ≫1.5R ⊙. We take the opportunity of the good multi-instrument coverage of this event to analyse the origin of type N bursts in the high corona. Reconnection of the expanding ejecta with the magnetic structure of a previous CME, launched about 8 hours earlier, injects electrons in the same manner as with type III bursts but into open field lines having a local dip and apex. The latter shape was created by magnetic reconnection between the expanding CME and neighbouring (open) streamer field lines. This particular flux tube shape in the high corona, between 5R ⊙ and 10R ⊙, explains the observed type N burst. Since the required magnetic configuration is only a transient phenomenon formed by reconnection, severe timing and topological constraints are present to form the observed decametric N burst. They are therefore expected to be rare features. © Springer 2007.
format JOUR
author Démoulin, P.
Klein, K.-L.
Goff, C.P.
Van Driel-Gesztelyi, L.
Culhane, J.L.
Mandrini, C.H.
Matthews, S.A.
Harra, L.K.
spellingShingle Démoulin, P.
Klein, K.-L.
Goff, C.P.
Van Driel-Gesztelyi, L.
Culhane, J.L.
Mandrini, C.H.
Matthews, S.A.
Harra, L.K.
Decametric N burst: A consequence of the interaction of two coronal mass ejections
author_facet Démoulin, P.
Klein, K.-L.
Goff, C.P.
Van Driel-Gesztelyi, L.
Culhane, J.L.
Mandrini, C.H.
Matthews, S.A.
Harra, L.K.
author_sort Démoulin, P.
title Decametric N burst: A consequence of the interaction of two coronal mass ejections
title_short Decametric N burst: A consequence of the interaction of two coronal mass ejections
title_full Decametric N burst: A consequence of the interaction of two coronal mass ejections
title_fullStr Decametric N burst: A consequence of the interaction of two coronal mass ejections
title_full_unstemmed Decametric N burst: A consequence of the interaction of two coronal mass ejections
title_sort decametric n burst: a consequence of the interaction of two coronal mass ejections
url http://hdl.handle.net/20.500.12110/paper_00380938_v240_n2_p301_Demoulin
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AT goffcp decametricnburstaconsequenceoftheinteractionoftwocoronalmassejections
AT vandrielgesztelyil decametricnburstaconsequenceoftheinteractionoftwocoronalmassejections
AT culhanejl decametricnburstaconsequenceoftheinteractionoftwocoronalmassejections
AT mandrinich decametricnburstaconsequenceoftheinteractionoftwocoronalmassejections
AT matthewssa decametricnburstaconsequenceoftheinteractionoftwocoronalmassejections
AT harralk decametricnburstaconsequenceoftheinteractionoftwocoronalmassejections
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