Interaction of p modes with a collection of thin magnetic tubes

Abstract

We investigate the net effect of a multitude of thin magnetic tubes on the energy of ambient acoustic p modes. A p mode, when incident on a thin magnetic flux tube, excites magnetohydrodynamic (MHD) tube waves. These tube waves propagate vertically along the flux tube carrying away energy from the p-mode cavity resulting in the absorption of incident p-mode energy. We calculate the absorption arising from the excitation of sausage MHD waves within a collection of many non-interacting magnetic flux tubes with differing plasma properties. We find that the shape and magnitude of the absorption, when compared with the observationally measured absorption, favours a model with a maximum-flux boundary condition applied at the photosphere and a narrow distribution of plasma β in an ensemble with mean β value between 0.5 and 1.