Jacket modes: Solar acoustic oscillations confined to regions surrounding sunspots and plage

T. J. Bogdan, P. S. Cally

Research output: Contribution to journalArticleResearchpeer-review

43 Citations (Scopus)


It is demonstrated by the application of classical eigenfunction expansion techniques that the interaction of an incident solar acoustic oscillation, or p-mode, with a scattering obstacle - such as a sunspot - involves not only the scattering of the incident p-mode into other p-modes of like frequency (mode mixing), but also the generation of an acoustic halo localized like a "jacket" about the scatterer. This halo oscillates at the same frequency as the incident p-mode and is composed of a superposition of a continuous spectrum of modes referred to as jacket modes. It is pointed out that these jacket modes should appear as a broad enhancement to the background power underlying the p-mode ridges in k-ω diagrams for regions in close proximity to sunspots and the boundaries of plage. The basic results draw upon a remarkable analogy between the oscillations of an adiabatically stratified plane-parallel polytrope and the wave functions for the hydrogen atom: the laterally propagating p-modes that participate in the mode mixing correspond to the negative-energy bounds states of the hydrogen atom, while the continuous spectrum of jacket modes corresponds to the continuum of positive-energy states in which the electron is not bound to the proton.

Original languageEnglish
Pages (from-to)919-928
Number of pages10
JournalThe Astrophysical Journal
Issue number2
Publication statusPublished - 10 Nov 1995


  • MHD
  • Sun: magnetic fields
  • Sun: oscillations
  • Sun: sunspots
  • Waves

Cite this