Lifetimes of High-[CLC][ITAL]l[/ITAL][/CLC] Solar [CLC][ITAL]p[/ITAL][/CLC]-Modes from Time-Distance Analysis

The amplitude of the cross-correlation function of solar p-modes in time-distance analysis decreases exponentially with travel distance (or travel time). We interpret this phenomenon as the dissipation of solar p-mode power and use the rate of decrease in the amplitude of the cross-correlation function to determine the lifetime of high-degree solar p-modes that cannot be accurately determined from the conventional method, measurements of line widths of p-mode power spectra, because of mode mixture. In this study, we determine the lifetimes of p-modes in the range l = 200-600 and ν = 2.5-5.5 mHz, where l is the spherical harmonic degree and ν is the frequency. The lifetime decreases with l for frequency less than about 4.7 mHz. For a fixed l, the frequency dependence has a general trend: the lifetime is approximately constant at intermediate frequency and decreases at high frequency.

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