A comparison of acoustic mode parameters using multi-spectral data

Abstract

We study the vanation in characteristics of the highdegree modes such as frequency, amplitude, line width with the type of spectral line used to observe the solar oscillation. The technique used here is the ring-diagram analysis, which has been proven a powerful tool in local helioseismic studies. The data sets include simultaneous observations obtained with the Ni I 676.8 nm from GONG, K I 769.9 nm from Magneto-Optical filters at Two Heights (MOTH) experiment and Na I D2 589.0 nm from MOTH experiment and Mount Wilson Observatory (MWO) during Austral summer of 2002-03. We use two different models to fit the power spectra obtained from the ring-diagram technique; the symmetric peak profile model and the asymmetric peak profile model. Our analysis clearly show that there is a significant variation in the mode amplitude for different spectral lines, however, mode frequencies and the line width or life-time of the modes are independent of the spectral line used to observe the oscillation.