A&A 415, 751-754 (2004)
Tube waves: Exact and approximateM. Stix
Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, 79104 Freiburg, Germany
(Received 8 December 2003 / Accepted 15 December 2003)
This note deals with magnetohydrodynamic body waves in a magnetic cylinder. It is shown that the solution obtained by the thin-tube expansion is, term by term, identical to the Taylor expansion of the exact solution. Each level of approximation adds a pair of modes, a slow and a fast one, and corrects the frequencies and eigenfunctions of the previous approximation. All eigenfrequencies, approximate and exact, can be read off from a single graph. All slow modes have phase velocities between the tube speed and , all fast modes have phase velocities above .
Key words: magnetohydrodynamics (MHD) -- waves -- methods: analytical -- Sun: magnetic fields
© ESO 2004