Wave Modes in Thick Photospheric Flux Tubes: Classification and Diagnostic Diagram

  1. C. T. Russell,
  2. E. R. Priest and
  3. L. C. Lee
  1. S. S. Hasan1 and
  2. T. Abdelatif2

Published Online: 21 MAR 2013

DOI: 10.1029/GM058p0093

Physics of Magnetic Flux Ropes

Physics of Magnetic Flux Ropes

How to Cite

Hasan, S. S. and Abdelatif, T. (2013) Wave Modes in Thick Photospheric Flux Tubes: Classification and Diagnostic Diagram, in Physics of Magnetic Flux Ropes (eds C. T. Russell, E. R. Priest and L. C. Lee), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM058p0093

Author Information

  1. 1

    Indin Institute of Astrophysics, Bangalore 560034, India

  2. 2

    School for Mathematics, Queen Mary College, London E1 4NS, U.K.

Publication History

  1. Published Online: 21 MAR 2013
  2. Published Print: 1 JAN 1990

ISBN Information

Print ISBN: 9780875900261

Online ISBN: 9781118663868

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Keywords:

  • Solar photosphere;
  • Magnetic flux;
  • Astrophysics

Summary

We analyse the nature of wave motions in thick photospheric flux tubes. The aim of our investigation is to determine the normal modes of a stratified atmosphere with a vertical magnetic field and to discuss their properties. The results are displayed in the form of a diagnostic diagram. An interesting feature of the solutions is the existence of ‘avoided crossings”, which occur when adjacent order modes approach each other in the diagnostic diagram. We examine the nature of the modes by decomposing the eigenvectors into longitudinal and transverse components. In general, the character of a mode changes with height in the atmosphere. We apply our results to umbral oscillations and find that the observed oscillations with periods in the range 2–3 min, correspond to low order modes in our calculation. For low horizontal wave number K, the modes, in the photosphere, have almost equal contributions from longitudinal and transverse components. As K increases, the transverse component begins to dominate. In the chromosphere, the modes are essentially transverse and can be identified with slow modes.