JACKET MODES - SOLAR ACOUSTIC-OSCILLATIONS CONFINED TO REGIONS SURROUNDING SUNSPOTS AND PLAGE

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-omega 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.