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dc.contributor.author
Démoulin, Pascal
dc.contributor.author
Dasso, Sergio Ricardo
dc.date.available
2017-07-14T17:18:48Z
dc.date.issued
2009-09-15
dc.identifier.citation
Démoulin, Pascal; Dasso, Sergio Ricardo; Magnetic cloud models with bent and oblate cross-section boundary; EDP Sciences; Astronomy and Astrophysics; 507; 2; 15-9-2009; 969-980
dc.identifier.issn
0004-6361
dc.identifier.uri
http://hdl.handle.net/11336/20579
dc.description.abstract
Context. Magnetic clouds (MCs) are formed by magnetic flux ropes that are ejected from the Sun as coronal mass ejections. These structures generally have low plasma beta and travel through the interplanetary medium interacting with the surrounding solar wind. Thus, the dynamical evolution of the internal magnetic structure of a MC is a consequence of both the conditions of its environment
and of its own dynamical laws, which are mainly dominated by magnetic forces.
Aims. With in-situ observations the magnetic field is only measured along the trajectory of the spacecraft across the MC. Therefore, a magnetic model is needed to reconstruct the magnetic configuration of the encountered MC. The main aim of the present work is to extend the widely used cylindrical model to arbitrary cross-section shapes. Methods. The flux rope boundary is parametrized to account for a broad range of shapes. Then, the internal structure of the flux rope is computed by expressing the magnetic field as a series of modes of a linear force-free field.
Results. We analyze the magnetic field profile along straight cuts through the flux rope, in order to simulate the spacecraft crossing through a MC. We find that the magnetic field orientation is only weakly affected by the shape of the MC boundary. Therefore, the MC axis can approximately be found by the typical methods previously used (e.g., minimum variance). The boundary shape affects
the magnetic field strength most. The measurement of how much the field strength peaks along the crossing provides an estimation of the aspect ratio of the flux-rope cross-section. The asymmetry of the field strength between the front and the back of the MC, after correcting for the time evolution (i.e., its aging during the observation of the MC), provides an estimation of the cross-section global bending. A flat or/and bent cross-section requires a large anisotropy of the total pressure imposed at the MC boundary by the surrounding medium. Conclusions. The new theoretical model developed here relaxes the cylindrical symmetry hypothesis. It is designed to estimate the cross-section shape of the flux rope using the in-situ data of one spacecraft. This allows a more accurate determination of the global
quantities, such as magnetic fluxes and helicity. These quantities are especially important for both linking an observed MC to its solar source and for understanding the corresponding evolution.
dc.format
application/pdf
dc.language.iso
eng
dc.publisher
EDP Sciences
dc.rights
info:eu-repo/semantics/openAccess
dc.rights.uri
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.subject
Solar Wind
dc.subject
Magnetic Clouds
dc.subject.classification
Astronomía
dc.subject.classification
Ciencias Físicas
dc.subject.classification
CIENCIAS NATURALES Y EXACTAS
dc.title
Magnetic cloud models with bent and oblate cross-section boundary
dc.type
info:eu-repo/semantics/article
dc.type
info:ar-repo/semantics/artículo
dc.type
info:eu-repo/semantics/publishedVersion
dc.date.updated
2017-07-14T14:08:00Z
dc.journal.volume
507
dc.journal.number
2
dc.journal.pagination
969-980
dc.journal.pais
Francia
dc.journal.ciudad
Paris
dc.description.fil
Fil: Démoulin, Pascal. Centre National de la Recherche Scientifique. Observatoire de Paris; Francia
dc.description.fil
Fil: Dasso, Sergio Ricardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina
dc.journal.title
Astronomy and Astrophysics
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/doi/http://dx.doi.org/10.1051/0004-6361/200912645
dc.relation.alternativeid
info:eu-repo/semantics/altIdentifier/url/https://www.aanda.org/articles/aa/abs/2009/44/aa12645-09/aa12645-09.html
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