Effects of line asymmetries on the determination of solar internal structure

Despite the strong evidence that the peaks in the spectrum of solar oscilla tions are asymmetric, most determinations of mode frequencies have been bas ed on fits of symmetric Lorentzian profiles to the Fourier or power spectra of oscillation time strings. The systematic errors resulting from neglecti ng the line asymmetry could have serious effects on inversions for the sola r internal structure and rotation. Here we analyse artificial data based on simple models of the intrinsic line asymmetry, using GONG mode parameters with asymmetries found by one of us (Rosenthal 1998b). By fitting Lorentzia ns to the resulting spectra, we estimate the likely properties of the error s introduced in the frequencies. We discuss whether these frequency shifts have a form similar to the near-surface layers uncertainties and are theref ore suppressed in the solar structure inversion. We also estimate directly their contribution, if any, in the solar sound-speed and density determinat ions using the SOLA technique.