A new model-independent method to compute magnetic helicity in magnetic clouds
Context. Magnetic clouds are transient magnetic structures expulsed from the Sun that travel toward the external heliosphere carrying a significant amount of magnetic flux and helicity. Aims. To improve our understanding of magnetic clouds in relation to their solar source regions, we need a reliabl...
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2006
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00046361_v455_n1_p349_Dasso http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=artiaex&d=paper_00046361_v455_n1_p349_Dasso_oai |
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I28-R145-paper_00046361_v455_n1_p349_Dasso_oai2020-10-19 Dasso, S. Mandrini, C.H. Démoulin, P. Luoni, M.L. 2006 Context. Magnetic clouds are transient magnetic structures expulsed from the Sun that travel toward the external heliosphere carrying a significant amount of magnetic flux and helicity. Aims. To improve our understanding of magnetic clouds in relation to their solar source regions, we need a reliable method to compute magnetic flux and helicity in both regions. Here we evaluate the sensitivity of the results using different models, methods and magnetic cloud boundaries applied to the same magnetic cloud data. Methods. The magnetic cloud was observed by the spacecraft Wind on October 18-20, 1995. We analyze this cloud considering four different theoretical configurations (two force free and two non-force free) that have been previously proposed to model cloud fields. These four models are applied using two methods to determine the orientation of the cloud axis: minimum variance and simultaneous fitting. Finally, we present a new method to obtain the axial and azimuthal magnetic fluxes and helicity directly from the observed magnetic field when rotated to the cloud frame. Results, The results from the fitted models have biases that we analyze, The new method determines the centre and the rear boundary of the flux rope when the front boundary is known. It also gives two independent measurements in the front and back parts for the fluxes and helicity; they are free of model and boundary biases. We deduce that the leading flux of the magnetic cloud had reconnected with the overtaken solar wind magnetic field and estimate the fluxes and helicity present in the full cloud before this reconnection. © ESO 2006. Fil:Dasso, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Mandrini, C.H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Luoni, M.L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. application/pdf http://hdl.handle.net/20.500.12110/paper_00046361_v455_n1_p349_Dasso info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar Astron. Astrophys. 2006;455(1):349-359 Interplanetary medium Sun: coronal mass ejections (CMEs) Sun: magnetic fields Magnetic fields Magnetic flux Spacecraft Sun Interplanetary medium Magnetic cloud boundaries Sun: coronal mass ejections (CME) Sun: magnetic fields Astronomy A new model-independent method to compute magnetic helicity in magnetic clouds info:eu-repo/semantics/article info:ar-repo/semantics/artículo info:eu-repo/semantics/publishedVersion http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=artiaex&d=paper_00046361_v455_n1_p349_Dasso_oai |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-145 |
| collection |
Repositorio Digital de la Universidad de Buenos Aires (UBA) |
| topic |
Interplanetary medium Sun: coronal mass ejections (CMEs) Sun: magnetic fields Magnetic fields Magnetic flux Spacecraft Sun Interplanetary medium Magnetic cloud boundaries Sun: coronal mass ejections (CME) Sun: magnetic fields Astronomy |
| spellingShingle |
Interplanetary medium Sun: coronal mass ejections (CMEs) Sun: magnetic fields Magnetic fields Magnetic flux Spacecraft Sun Interplanetary medium Magnetic cloud boundaries Sun: coronal mass ejections (CME) Sun: magnetic fields Astronomy Dasso, S. Mandrini, C.H. Démoulin, P. Luoni, M.L. A new model-independent method to compute magnetic helicity in magnetic clouds |
| topic_facet |
Interplanetary medium Sun: coronal mass ejections (CMEs) Sun: magnetic fields Magnetic fields Magnetic flux Spacecraft Sun Interplanetary medium Magnetic cloud boundaries Sun: coronal mass ejections (CME) Sun: magnetic fields Astronomy |
| description |
Context. Magnetic clouds are transient magnetic structures expulsed from the Sun that travel toward the external heliosphere carrying a significant amount of magnetic flux and helicity. Aims. To improve our understanding of magnetic clouds in relation to their solar source regions, we need a reliable method to compute magnetic flux and helicity in both regions. Here we evaluate the sensitivity of the results using different models, methods and magnetic cloud boundaries applied to the same magnetic cloud data. Methods. The magnetic cloud was observed by the spacecraft Wind on October 18-20, 1995. We analyze this cloud considering four different theoretical configurations (two force free and two non-force free) that have been previously proposed to model cloud fields. These four models are applied using two methods to determine the orientation of the cloud axis: minimum variance and simultaneous fitting. Finally, we present a new method to obtain the axial and azimuthal magnetic fluxes and helicity directly from the observed magnetic field when rotated to the cloud frame. Results, The results from the fitted models have biases that we analyze, The new method determines the centre and the rear boundary of the flux rope when the front boundary is known. It also gives two independent measurements in the front and back parts for the fluxes and helicity; they are free of model and boundary biases. We deduce that the leading flux of the magnetic cloud had reconnected with the overtaken solar wind magnetic field and estimate the fluxes and helicity present in the full cloud before this reconnection. © ESO 2006. |
| format |
Artículo Artículo publishedVersion |
| author |
Dasso, S. Mandrini, C.H. Démoulin, P. Luoni, M.L. |
| author_facet |
Dasso, S. Mandrini, C.H. Démoulin, P. Luoni, M.L. |
| author_sort |
Dasso, S. |
| title |
A new model-independent method to compute magnetic helicity in magnetic clouds |
| title_short |
A new model-independent method to compute magnetic helicity in magnetic clouds |
| title_full |
A new model-independent method to compute magnetic helicity in magnetic clouds |
| title_fullStr |
A new model-independent method to compute magnetic helicity in magnetic clouds |
| title_full_unstemmed |
A new model-independent method to compute magnetic helicity in magnetic clouds |
| title_sort |
new model-independent method to compute magnetic helicity in magnetic clouds |
| publishDate |
2006 |
| url |
http://hdl.handle.net/20.500.12110/paper_00046361_v455_n1_p349_Dasso http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=artiaex&d=paper_00046361_v455_n1_p349_Dasso_oai |
| work_keys_str_mv |
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| _version_ |
1766026498091778048 |