The contribution by thin magnetic flux tubes to p-mode line widths

The contribution to p-mode line widths from the excitation of tube mode osc illations on an individual magnetic fibril is computed. An idealized model of the fibril within the photosphere is implemented, consisting of a vertic al, thin magnetic flux tube embedded in a plane-parallel isentropic polytro pe of index m. Bogdan et al. considered a similar model but imposed a stres s-free boundary condition at the top of the photosphere, which acts to refl ect any upward-propagating tube waves completely back down into the tube. T he stress-free boundary condition neglects a possibly important physical pr ocess: the loss of energy to the upper solar atmosphere by the excitation o f waves in the chromosphere and corona. Using simple models of the solar ch romosphere and corona, we explore the consequences of applying various boun dary conditions. The resultant upward energy fluxes are not large, but surp risingly the more realistic upper boundary conditions lead to a significant increase in kink mode flux out the bottom. Nevertheless, the sausage mode remains dominant in cases of interest and is essentially unaffected by the new boundary conditions. Consequently, the resultant total p-mode line widt h computed here can account for only a few percent of the observed line wid th.