Fast magnetohydrodynamic oscillations in a force-free line-tied coronal arcade

A. J. Diaz; T. Zaqarashvili; B. Roberts

doi:10.1051/0004-6361:20054430

Fast magnetohydrodynamic oscillations in a force-free line-tied coronal arcade

A. J. Diaz, T. Zaqarashvili, B. Roberts

Applied Mathematics

Research output: Contribution to journal › Article › peer-review

Abstract

Aims. We discuss a simple model of a line-tied coronal arcade with piecewise constant density to explore the effects of curvature on radially polarised fast modes.

Methods. A partial differential equation is derived for the velocity perturbation of the fast modes and it is solved analytically in terms of Bessel functions of half integer order, obtaining a dispersion relation.

Results. The properties of the modes are studied in terms of the parameters. All the modes are leaky under these conditions. Besides the usual kink and sausage modes, new families are described: the vertical, swaying ( longitudinal), and rocking modes arise.

Conclusions. The damping rates are similar to observed rates. For thin arcades the modes are markedly different from those of a straight slab and resemble more the modes of a circular membrane.

Original language	English
Pages (from-to)	709-717
Number of pages	9
Journal	Experimental Astronomy
Volume	455
DOIs	https://doi.org/10.1051/0004-6361:20054430
Publication status	Published - Aug 2006

Keywords

Sun : oscillations
Sun : magnetic fields
Sun : corona
MAGNETIC-FLUX TUBES
FAST MHD OSCILLATIONS
LOOP OSCILLATIONS
KINK OSCILLATIONS
VERTICAL OSCILLATIONS
WAVE-PROPAGATION
LEAKY
MAGNETOSPHERE
RESONANCES
CURVATURE

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10.1051/0004-6361:20054430

Cite this

@article{d33243c2ac2f4a9da61fd78241e48dc0,

title = "Fast magnetohydrodynamic oscillations in a force-free line-tied coronal arcade",

abstract = "Aims. We discuss a simple model of a line-tied coronal arcade with piecewise constant density to explore the effects of curvature on radially polarised fast modes.Methods. A partial differential equation is derived for the velocity perturbation of the fast modes and it is solved analytically in terms of Bessel functions of half integer order, obtaining a dispersion relation.Results. The properties of the modes are studied in terms of the parameters. All the modes are leaky under these conditions. Besides the usual kink and sausage modes, new families are described: the vertical, swaying ( longitudinal), and rocking modes arise.Conclusions. The damping rates are similar to observed rates. For thin arcades the modes are markedly different from those of a straight slab and resemble more the modes of a circular membrane.",

keywords = "Sun : oscillations, Sun : magnetic fields, Sun : corona, MAGNETIC-FLUX TUBES, FAST MHD OSCILLATIONS, LOOP OSCILLATIONS, KINK OSCILLATIONS, VERTICAL OSCILLATIONS, WAVE-PROPAGATION, LEAKY, MAGNETOSPHERE, RESONANCES, CURVATURE",

author = "Diaz, {A. J.} and T. Zaqarashvili and B. Roberts",

year = "2006",

month = aug,

doi = "10.1051/0004-6361:20054430",

language = "English",

volume = "455",

pages = "709--717",

journal = "Experimental Astronomy",

publisher = "Springer",

}

TY - JOUR

T1 - Fast magnetohydrodynamic oscillations in a force-free line-tied coronal arcade

AU - Diaz, A. J.

AU - Zaqarashvili, T.

AU - Roberts, B.

PY - 2006/8

Y1 - 2006/8

N2 - Aims. We discuss a simple model of a line-tied coronal arcade with piecewise constant density to explore the effects of curvature on radially polarised fast modes.Methods. A partial differential equation is derived for the velocity perturbation of the fast modes and it is solved analytically in terms of Bessel functions of half integer order, obtaining a dispersion relation.Results. The properties of the modes are studied in terms of the parameters. All the modes are leaky under these conditions. Besides the usual kink and sausage modes, new families are described: the vertical, swaying ( longitudinal), and rocking modes arise.Conclusions. The damping rates are similar to observed rates. For thin arcades the modes are markedly different from those of a straight slab and resemble more the modes of a circular membrane.

AB - Aims. We discuss a simple model of a line-tied coronal arcade with piecewise constant density to explore the effects of curvature on radially polarised fast modes.Methods. A partial differential equation is derived for the velocity perturbation of the fast modes and it is solved analytically in terms of Bessel functions of half integer order, obtaining a dispersion relation.Results. The properties of the modes are studied in terms of the parameters. All the modes are leaky under these conditions. Besides the usual kink and sausage modes, new families are described: the vertical, swaying ( longitudinal), and rocking modes arise.Conclusions. The damping rates are similar to observed rates. For thin arcades the modes are markedly different from those of a straight slab and resemble more the modes of a circular membrane.

KW - Sun : oscillations

KW - Sun : magnetic fields

KW - Sun : corona

KW - MAGNETIC-FLUX TUBES

KW - FAST MHD OSCILLATIONS

KW - LOOP OSCILLATIONS

KW - KINK OSCILLATIONS

KW - VERTICAL OSCILLATIONS

KW - WAVE-PROPAGATION

KW - LEAKY

KW - MAGNETOSPHERE

KW - RESONANCES

KW - CURVATURE

U2 - 10.1051/0004-6361:20054430

DO - 10.1051/0004-6361:20054430

M3 - Article

VL - 455

SP - 709

EP - 717

JO - Experimental Astronomy

JF - Experimental Astronomy

ER -

Fast magnetohydrodynamic oscillations in a force-free line-tied coronal arcade

Abstract

Keywords

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