Expansion of magnetic clouds in the outer heliosphere

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Context. A large amount of magnetized plasma is frequently ejected from the Sun as coronal mass ejections (CMEs). Some of these ejections are detected in the solar wind as magnetic clouds (MCs) that have flux rope signatures. Aims. Magnetic clouds are structures that typically expand in the inner he...

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Autores principales:	Gulisano, A.M., Démoulin, P., Dasso, S., Rodriguez, L.
Formato:	JOUR
Materias:	Interplanetary medium Magnetic fields Magnetohydrodynamics (MHD) Solar wind Sun: coronal mass ejections (CMEs) Astronomical units Coronal mass ejection Expansion properties Expansion rate Flux ropes Heliospheres In-situ Linear functions Linear velocity Magnetic clouds Magnetized plasmas Mean magnetic field Minimum variance Outer heliosphere Plasma measurement Plasma parameter Power-law Self-similar Strong field Sun: coronal mass ejection Temporal evolution Ulysses spacecraft Velocity profiles Magnetohydrodynamics Magnetoplasma Rope Solar system Velocity
Acceso en línea:	http://hdl.handle.net/20.500.12110/paper_00046361_v543_n_p_Gulisano
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

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spelling	todo:paper_00046361_v543_n_p_Gulisano2023-10-03T14:00:42Z Expansion of magnetic clouds in the outer heliosphere Gulisano, A.M. Démoulin, P. Dasso, S. Rodriguez, L. Interplanetary medium Magnetic fields Magnetohydrodynamics (MHD) Solar wind Sun: coronal mass ejections (CMEs) Astronomical units Coronal mass ejection Expansion properties Expansion rate Flux ropes Heliospheres In-situ Interplanetary medium Linear functions Linear velocity Magnetic clouds Magnetized plasmas Mean magnetic field Minimum variance Outer heliosphere Plasma measurement Plasma parameter Power-law Self-similar Strong field Sun: coronal mass ejection Temporal evolution Ulysses spacecraft Velocity profiles Magnetic fields Magnetohydrodynamics Magnetoplasma Rope Solar system Solar wind Velocity Context. A large amount of magnetized plasma is frequently ejected from the Sun as coronal mass ejections (CMEs). Some of these ejections are detected in the solar wind as magnetic clouds (MCs) that have flux rope signatures. Aims. Magnetic clouds are structures that typically expand in the inner heliosphere. We derive the expansion properties of MCs in the outer heliosphere from one to five astronomical units to compare them with those in the inner heliosphere. Methods. We analyze MCs observed by the Ulysses spacecraft using in situ magnetic field and plasma measurements. The MC boundaries are defined in the MC frame after defining the MC axis with a minimum variance method applied only to the flux rope structure. As in the inner heliosphere, a large fraction of the velocity profile within MCs is close to a linear function of time. This is indicative of a self-similar expansion and a MC size that locally follows a power-law of the solar distance with an exponent called ζ. We derive the value of ζ from the in situ velocity data. Results. We analyze separately the non-perturbed MCs (cases showing a linear velocity profile almost for the full event), and perturbed MCs (cases showing a strongly distorted velocity profile). We find that non-perturbed MCs expand with a similar non-dimensional expansion rate (ζ = 1.05 ± 0.34), i.e. slightly faster than at the solar distance and in the inner heliosphere (ζ = 0.91 ± 0.23). The subset of perturbed MCs expands, as in the inner heliosphere, at a significantly lower rate and with a larger dispersion (ζ = 0.28 ± 0.52) as expected from the temporal evolution found in numerical simulations. This local measure of the expansion also agrees with the distribution with distance of MC size, mean magnetic field, and plasma parameters. The MCs interacting with a strong field region, e.g. another MC, have the most variable expansion rate (ranging from compression to over-expansion). © 2012 ESO. Fil:Gulisano, A.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Dasso, S. 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_00046361_v543_n_p_Gulisano
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Interplanetary medium Magnetic fields Magnetohydrodynamics (MHD) Solar wind Sun: coronal mass ejections (CMEs) Astronomical units Coronal mass ejection Expansion properties Expansion rate Flux ropes Heliospheres In-situ Interplanetary medium Linear functions Linear velocity Magnetic clouds Magnetized plasmas Mean magnetic field Minimum variance Outer heliosphere Plasma measurement Plasma parameter Power-law Self-similar Strong field Sun: coronal mass ejection Temporal evolution Ulysses spacecraft Velocity profiles Magnetic fields Magnetohydrodynamics Magnetoplasma Rope Solar system Solar wind Velocity
spellingShingle	Interplanetary medium Magnetic fields Magnetohydrodynamics (MHD) Solar wind Sun: coronal mass ejections (CMEs) Astronomical units Coronal mass ejection Expansion properties Expansion rate Flux ropes Heliospheres In-situ Interplanetary medium Linear functions Linear velocity Magnetic clouds Magnetized plasmas Mean magnetic field Minimum variance Outer heliosphere Plasma measurement Plasma parameter Power-law Self-similar Strong field Sun: coronal mass ejection Temporal evolution Ulysses spacecraft Velocity profiles Magnetic fields Magnetohydrodynamics Magnetoplasma Rope Solar system Solar wind Velocity Gulisano, A.M. Démoulin, P. Dasso, S. Rodriguez, L. Expansion of magnetic clouds in the outer heliosphere
topic_facet	Interplanetary medium Magnetic fields Magnetohydrodynamics (MHD) Solar wind Sun: coronal mass ejections (CMEs) Astronomical units Coronal mass ejection Expansion properties Expansion rate Flux ropes Heliospheres In-situ Interplanetary medium Linear functions Linear velocity Magnetic clouds Magnetized plasmas Mean magnetic field Minimum variance Outer heliosphere Plasma measurement Plasma parameter Power-law Self-similar Strong field Sun: coronal mass ejection Temporal evolution Ulysses spacecraft Velocity profiles Magnetic fields Magnetohydrodynamics Magnetoplasma Rope Solar system Solar wind Velocity
description	Context. A large amount of magnetized plasma is frequently ejected from the Sun as coronal mass ejections (CMEs). Some of these ejections are detected in the solar wind as magnetic clouds (MCs) that have flux rope signatures. Aims. Magnetic clouds are structures that typically expand in the inner heliosphere. We derive the expansion properties of MCs in the outer heliosphere from one to five astronomical units to compare them with those in the inner heliosphere. Methods. We analyze MCs observed by the Ulysses spacecraft using in situ magnetic field and plasma measurements. The MC boundaries are defined in the MC frame after defining the MC axis with a minimum variance method applied only to the flux rope structure. As in the inner heliosphere, a large fraction of the velocity profile within MCs is close to a linear function of time. This is indicative of a self-similar expansion and a MC size that locally follows a power-law of the solar distance with an exponent called ζ. We derive the value of ζ from the in situ velocity data. Results. We analyze separately the non-perturbed MCs (cases showing a linear velocity profile almost for the full event), and perturbed MCs (cases showing a strongly distorted velocity profile). We find that non-perturbed MCs expand with a similar non-dimensional expansion rate (ζ = 1.05 ± 0.34), i.e. slightly faster than at the solar distance and in the inner heliosphere (ζ = 0.91 ± 0.23). The subset of perturbed MCs expands, as in the inner heliosphere, at a significantly lower rate and with a larger dispersion (ζ = 0.28 ± 0.52) as expected from the temporal evolution found in numerical simulations. This local measure of the expansion also agrees with the distribution with distance of MC size, mean magnetic field, and plasma parameters. The MCs interacting with a strong field region, e.g. another MC, have the most variable expansion rate (ranging from compression to over-expansion). © 2012 ESO.
format	JOUR
author	Gulisano, A.M. Démoulin, P. Dasso, S. Rodriguez, L.
author_facet	Gulisano, A.M. Démoulin, P. Dasso, S. Rodriguez, L.
author_sort	Gulisano, A.M.
title	Expansion of magnetic clouds in the outer heliosphere
title_short	Expansion of magnetic clouds in the outer heliosphere
title_full	Expansion of magnetic clouds in the outer heliosphere
title_fullStr	Expansion of magnetic clouds in the outer heliosphere
title_full_unstemmed	Expansion of magnetic clouds in the outer heliosphere
title_sort	expansion of magnetic clouds in the outer heliosphere
url	http://hdl.handle.net/20.500.12110/paper_00046361_v543_n_p_Gulisano
work_keys_str_mv	AT gulisanoam expansionofmagneticcloudsintheouterheliosphere AT demoulinp expansionofmagneticcloudsintheouterheliosphere AT dassos expansionofmagneticcloudsintheouterheliosphere AT rodriguezl expansionofmagneticcloudsintheouterheliosphere
_version_	1782023961262948352

Expansion of magnetic clouds in the outer heliosphere

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