DETERMINATION OF THE LIFETIME OF HIGH-L SOLAR P-MODES FROM THE INTERACTION OF P-MODE WAVES WITH SUNSPOTS

We use the absorption of the solar p-mode waves in sunspots as a tool to determine the lifetime of the p-modes in the range l = 200-700. We measure the absorption coefficients of the p-modes of the sunspots wit h the helioseismology data taken by the Taiwan Oscillation Network and find that the absorption coefficients of all five sunspots decrease w ith the distance from the annular region, used to compute the absorpti on coefficients, to the central sunspot. This decrease of the absorpti on coefficients is interpreted as the effect of the finite p-mode life time. The measured absorption coefficients of the sunspot regions beco me negative when the distance from the annular region to the central s unspot is large. This phenomenon is also found in a quiet region. We i nterpret this phenomenon in two different ways: the effective acoustic emission and the observational center-to-limb effect. We set up two s imple models to relate the p-mode lifetime and effective emission stre ngth to the measured absorption coefficient. By fitting the measured a bsorption coefficient versus distance to the models, we obtain the lif etime and the strength of the effective acoustic emission for the mode s in the range l = 200-700. The measured p-mode lifetimes decrease wit h l and the frequency.