Free access article

A&A 415, 691-703 (2004)
DOI: 10.1051/0004-6361:20034625

The effect of anisotropy on the propagation of linear compressional waves in magnetic flux tubes: Applications to astrophysical plasmas

I. Ballai¹ and A. Marcu<sup>2

1</sup>  Space & Atmosphere Research Center (SPARC), Dept. of Applied Mathematics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH, UK
²  Babes-Bolyai University, Dept. of Theoretical Physics, 1 Kogalniceanu, 3400-Cluj Napoca, Romania

(Received 24 June 2003 / Accepted 6 November 2003 )

Abstract
The propagation of linear compressional waves is studied in magnetic flux tubes. The plasma inside and outside the tube is considered to be rarefied which confers an anisotropic character to the plasma. The anisotropy appears at different temperatures for parallel and perpendicular directions relative to the ambient magnetic field. The theoretical results are applied to study the effects of anisotropy and equilibrium steady flow on wave propagation in structures such as coronal plumes, the geomagnetic tail and anisotropic astrophysical jets. The obtained results show that the internal and/or external anisotropy has a very important effect on the propagation of linear compressional waves. The presence of a steady equilibrium flow in certain applications can change dramatically the propagation of the modes.

Key words: plasmas -- Sun: solar wind -- waves -- magnetic fields -- ISM: jets and outflow

Offprint request: I. Ballai, i.ballai@sheffield.ac.uk

© ESO 2004

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