Causes and consequences of magnetic cloud expansion
- Autores
- Démoulin, P.; Dasso, S.
- Año de publicación
- 2009
- Idioma
- inglés
- Tipo de recurso
- artículo
- Estado
- versión publicada
- Descripción
- Context. A magnetic cloud (MC) is a magnetic flux rope in the solar wind (SW), which, at 1 AU, is observed ∼2-5 days after its expulsion from the Sun. The associated solar eruption is observed as a coronal mass ejection (CME).Aims. Both the in situ observations of plasma velocity distribution and the increase in their size with solar distance demonstrate that MCs are strongly expanding structures. The aim of this work is to find the main causes of this expansion and to derive a model to explain the plasma velocity profiles typically observed inside MCs.Methods. We model the flux rope evolution as a series of force-free field states with two extreme limits: (a) ideal magneto-hydrodynamics (MHD) and (b) minimization of the magnetic energy with conserved magnetic helicity. We consider cylindrical flux ropes to reduce the problem to the integration of ordinary differential equations. This allows us to explore a wide variety of magnetic fields at a broad range of distances to the Sun.Results. We demonstrate that the rapid decrease in the total SW pressure with solar distance is the main driver of the flux-rope radial expansion. Other effects, such as the internal over-pressure, the radial distribution, and the amount of twist within the flux rope have a much weaker influence on the expansion. We demonstrate that any force-free flux rope will have a self-similar expansion if its total boundary pressure evolves as the inverse of its length to the fourth power. With the total pressure gradient observed in the SW, the radial expansion of flux ropes is close to self-similar with a nearly linear radial velocity profile across the flux rope, as observed. Moreover, we show that the expansion rate is proportional to the radius and to the global velocity away from the Sun.Conclusions. The simple and universal law found for the radial expansion of flux ropes in the SW predicts the typical size, magnetic structure, and radial velocity of MCs at various solar distances. © 2009 ESO.
Fil:Dasso, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. - Fuente
- Astron. Astrophys. 2009;498(2):551-566
- Materia
-
interplanetary medium
Sun: coronal mass ejections (CMEs)
Sun: magnetic fields
Boundary pressure
Coronal mass ejection
Cylindrical flux ropes
Expansion rate
Flux ropes
Force free fields
In-situ observations
interplanetary medium
Magnetic clouds
Magnetic energies
Magnetic flux ropes
Magnetic helicity
Plasma velocity
Radial distributions
Radial expansions
Radial velocity
Self-similar
Solar eruption
Sun: coronal mass ejections (CMEs)
Sun: magnetic fields
Astrophysics
Boundary layer flow
Energy conservation
Expansion
Fluid dynamics
Magnetic fields
Magnetic flux
Magnetic structure
Magnetohydrodynamics
Ordinary differential equations
Pressure gradient
Solar wind
Sun
Velocity
Velocity distribution
Solar energy - Nivel de accesibilidad
- acceso abierto
- Condiciones de uso
- http://creativecommons.org/licenses/by/2.5/ar
- Repositorio
- Institución
- Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales
- OAI Identificador
- paperaa:paper_00046361_v498_n2_p551_Demoulin
Ver los metadatos del registro completo
id |
BDUBAFCEN_ed48afc78b142b177be7332005b2c6c2 |
---|---|
oai_identifier_str |
paperaa:paper_00046361_v498_n2_p551_Demoulin |
network_acronym_str |
BDUBAFCEN |
repository_id_str |
1896 |
network_name_str |
Biblioteca Digital (UBA-FCEN) |
spelling |
Causes and consequences of magnetic cloud expansionDémoulin, P.Dasso, S.interplanetary mediumSun: coronal mass ejections (CMEs)Sun: magnetic fieldsBoundary pressureCoronal mass ejectionCylindrical flux ropesExpansion rateFlux ropesForce free fieldsIn-situ observationsinterplanetary mediumMagnetic cloudsMagnetic energiesMagnetic flux ropesMagnetic helicityPlasma velocityRadial distributionsRadial expansionsRadial velocitySelf-similarSolar eruptionSun: coronal mass ejections (CMEs)Sun: magnetic fieldsAstrophysicsBoundary layer flowEnergy conservationExpansionFluid dynamicsMagnetic fieldsMagnetic fluxMagnetic structureMagnetohydrodynamicsOrdinary differential equationsPressure gradientSolar windSunVelocityVelocity distributionSolar energyContext. A magnetic cloud (MC) is a magnetic flux rope in the solar wind (SW), which, at 1 AU, is observed ∼2-5 days after its expulsion from the Sun. The associated solar eruption is observed as a coronal mass ejection (CME).Aims. Both the in situ observations of plasma velocity distribution and the increase in their size with solar distance demonstrate that MCs are strongly expanding structures. The aim of this work is to find the main causes of this expansion and to derive a model to explain the plasma velocity profiles typically observed inside MCs.Methods. We model the flux rope evolution as a series of force-free field states with two extreme limits: (a) ideal magneto-hydrodynamics (MHD) and (b) minimization of the magnetic energy with conserved magnetic helicity. We consider cylindrical flux ropes to reduce the problem to the integration of ordinary differential equations. This allows us to explore a wide variety of magnetic fields at a broad range of distances to the Sun.Results. We demonstrate that the rapid decrease in the total SW pressure with solar distance is the main driver of the flux-rope radial expansion. Other effects, such as the internal over-pressure, the radial distribution, and the amount of twist within the flux rope have a much weaker influence on the expansion. We demonstrate that any force-free flux rope will have a self-similar expansion if its total boundary pressure evolves as the inverse of its length to the fourth power. With the total pressure gradient observed in the SW, the radial expansion of flux ropes is close to self-similar with a nearly linear radial velocity profile across the flux rope, as observed. Moreover, we show that the expansion rate is proportional to the radius and to the global velocity away from the Sun.Conclusions. The simple and universal law found for the radial expansion of flux ropes in the SW predicts the typical size, magnetic structure, and radial velocity of MCs at various solar distances. © 2009 ESO.Fil:Dasso, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.2009info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfhttp://hdl.handle.net/20.500.12110/paper_00046361_v498_n2_p551_DemoulinAstron. Astrophys. 2009;498(2):551-566reponame:Biblioteca Digital (UBA-FCEN)instname:Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturalesinstacron:UBA-FCENenginfo:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by/2.5/ar2025-09-29T13:42:57Zpaperaa:paper_00046361_v498_n2_p551_DemoulinInstitucionalhttps://digital.bl.fcen.uba.ar/Universidad públicaNo correspondehttps://digital.bl.fcen.uba.ar/cgi-bin/oaiserver.cgiana@bl.fcen.uba.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:18962025-09-29 13:42:59.049Biblioteca Digital (UBA-FCEN) - Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturalesfalse |
dc.title.none.fl_str_mv |
Causes and consequences of magnetic cloud expansion |
title |
Causes and consequences of magnetic cloud expansion |
spellingShingle |
Causes and consequences of magnetic cloud expansion Démoulin, P. interplanetary medium Sun: coronal mass ejections (CMEs) Sun: magnetic fields Boundary pressure Coronal mass ejection Cylindrical flux ropes Expansion rate Flux ropes Force free fields In-situ observations interplanetary medium Magnetic clouds Magnetic energies Magnetic flux ropes Magnetic helicity Plasma velocity Radial distributions Radial expansions Radial velocity Self-similar Solar eruption Sun: coronal mass ejections (CMEs) Sun: magnetic fields Astrophysics Boundary layer flow Energy conservation Expansion Fluid dynamics Magnetic fields Magnetic flux Magnetic structure Magnetohydrodynamics Ordinary differential equations Pressure gradient Solar wind Sun Velocity Velocity distribution Solar energy |
title_short |
Causes and consequences of magnetic cloud expansion |
title_full |
Causes and consequences of magnetic cloud expansion |
title_fullStr |
Causes and consequences of magnetic cloud expansion |
title_full_unstemmed |
Causes and consequences of magnetic cloud expansion |
title_sort |
Causes and consequences of magnetic cloud expansion |
dc.creator.none.fl_str_mv |
Démoulin, P. Dasso, S. |
author |
Démoulin, P. |
author_facet |
Démoulin, P. Dasso, S. |
author_role |
author |
author2 |
Dasso, S. |
author2_role |
author |
dc.subject.none.fl_str_mv |
interplanetary medium Sun: coronal mass ejections (CMEs) Sun: magnetic fields Boundary pressure Coronal mass ejection Cylindrical flux ropes Expansion rate Flux ropes Force free fields In-situ observations interplanetary medium Magnetic clouds Magnetic energies Magnetic flux ropes Magnetic helicity Plasma velocity Radial distributions Radial expansions Radial velocity Self-similar Solar eruption Sun: coronal mass ejections (CMEs) Sun: magnetic fields Astrophysics Boundary layer flow Energy conservation Expansion Fluid dynamics Magnetic fields Magnetic flux Magnetic structure Magnetohydrodynamics Ordinary differential equations Pressure gradient Solar wind Sun Velocity Velocity distribution Solar energy |
topic |
interplanetary medium Sun: coronal mass ejections (CMEs) Sun: magnetic fields Boundary pressure Coronal mass ejection Cylindrical flux ropes Expansion rate Flux ropes Force free fields In-situ observations interplanetary medium Magnetic clouds Magnetic energies Magnetic flux ropes Magnetic helicity Plasma velocity Radial distributions Radial expansions Radial velocity Self-similar Solar eruption Sun: coronal mass ejections (CMEs) Sun: magnetic fields Astrophysics Boundary layer flow Energy conservation Expansion Fluid dynamics Magnetic fields Magnetic flux Magnetic structure Magnetohydrodynamics Ordinary differential equations Pressure gradient Solar wind Sun Velocity Velocity distribution Solar energy |
dc.description.none.fl_txt_mv |
Context. A magnetic cloud (MC) is a magnetic flux rope in the solar wind (SW), which, at 1 AU, is observed ∼2-5 days after its expulsion from the Sun. The associated solar eruption is observed as a coronal mass ejection (CME).Aims. Both the in situ observations of plasma velocity distribution and the increase in their size with solar distance demonstrate that MCs are strongly expanding structures. The aim of this work is to find the main causes of this expansion and to derive a model to explain the plasma velocity profiles typically observed inside MCs.Methods. We model the flux rope evolution as a series of force-free field states with two extreme limits: (a) ideal magneto-hydrodynamics (MHD) and (b) minimization of the magnetic energy with conserved magnetic helicity. We consider cylindrical flux ropes to reduce the problem to the integration of ordinary differential equations. This allows us to explore a wide variety of magnetic fields at a broad range of distances to the Sun.Results. We demonstrate that the rapid decrease in the total SW pressure with solar distance is the main driver of the flux-rope radial expansion. Other effects, such as the internal over-pressure, the radial distribution, and the amount of twist within the flux rope have a much weaker influence on the expansion. We demonstrate that any force-free flux rope will have a self-similar expansion if its total boundary pressure evolves as the inverse of its length to the fourth power. With the total pressure gradient observed in the SW, the radial expansion of flux ropes is close to self-similar with a nearly linear radial velocity profile across the flux rope, as observed. Moreover, we show that the expansion rate is proportional to the radius and to the global velocity away from the Sun.Conclusions. The simple and universal law found for the radial expansion of flux ropes in the SW predicts the typical size, magnetic structure, and radial velocity of MCs at various solar distances. © 2009 ESO. Fil:Dasso, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. |
description |
Context. A magnetic cloud (MC) is a magnetic flux rope in the solar wind (SW), which, at 1 AU, is observed ∼2-5 days after its expulsion from the Sun. The associated solar eruption is observed as a coronal mass ejection (CME).Aims. Both the in situ observations of plasma velocity distribution and the increase in their size with solar distance demonstrate that MCs are strongly expanding structures. The aim of this work is to find the main causes of this expansion and to derive a model to explain the plasma velocity profiles typically observed inside MCs.Methods. We model the flux rope evolution as a series of force-free field states with two extreme limits: (a) ideal magneto-hydrodynamics (MHD) and (b) minimization of the magnetic energy with conserved magnetic helicity. We consider cylindrical flux ropes to reduce the problem to the integration of ordinary differential equations. This allows us to explore a wide variety of magnetic fields at a broad range of distances to the Sun.Results. We demonstrate that the rapid decrease in the total SW pressure with solar distance is the main driver of the flux-rope radial expansion. Other effects, such as the internal over-pressure, the radial distribution, and the amount of twist within the flux rope have a much weaker influence on the expansion. We demonstrate that any force-free flux rope will have a self-similar expansion if its total boundary pressure evolves as the inverse of its length to the fourth power. With the total pressure gradient observed in the SW, the radial expansion of flux ropes is close to self-similar with a nearly linear radial velocity profile across the flux rope, as observed. Moreover, we show that the expansion rate is proportional to the radius and to the global velocity away from the Sun.Conclusions. The simple and universal law found for the radial expansion of flux ropes in the SW predicts the typical size, magnetic structure, and radial velocity of MCs at various solar distances. © 2009 ESO. |
publishDate |
2009 |
dc.date.none.fl_str_mv |
2009 |
dc.type.none.fl_str_mv |
info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion http://purl.org/coar/resource_type/c_6501 info:ar-repo/semantics/articulo |
format |
article |
status_str |
publishedVersion |
dc.identifier.none.fl_str_mv |
http://hdl.handle.net/20.500.12110/paper_00046361_v498_n2_p551_Demoulin |
url |
http://hdl.handle.net/20.500.12110/paper_00046361_v498_n2_p551_Demoulin |
dc.language.none.fl_str_mv |
eng |
language |
eng |
dc.rights.none.fl_str_mv |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar |
eu_rights_str_mv |
openAccess |
rights_invalid_str_mv |
http://creativecommons.org/licenses/by/2.5/ar |
dc.format.none.fl_str_mv |
application/pdf |
dc.source.none.fl_str_mv |
Astron. Astrophys. 2009;498(2):551-566 reponame:Biblioteca Digital (UBA-FCEN) instname:Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales instacron:UBA-FCEN |
reponame_str |
Biblioteca Digital (UBA-FCEN) |
collection |
Biblioteca Digital (UBA-FCEN) |
instname_str |
Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales |
instacron_str |
UBA-FCEN |
institution |
UBA-FCEN |
repository.name.fl_str_mv |
Biblioteca Digital (UBA-FCEN) - Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales |
repository.mail.fl_str_mv |
ana@bl.fcen.uba.ar |
_version_ |
1844618736302030848 |
score |
13.070432 |