Effects of Dispersion of Wave Packets in the Determination of Lifetimes of High-Degree Solar p Modes from Time – Distance Analysis: MDI Data |
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Authors: | Dean-Yi Chou Oleg Ladenkov |
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Affiliation: | (1) Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, 30043, Taiwan |
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Abstract: | The cross-correlation function of solar p modes in a time – distance analysis changes with travel distance (or travel time). The exponential decrease in the amplitude of the cross-correlation function with travel distance has been interpreted as the dissipation of solar p-mode power and used to determine the lifetimes of high-degree p modes. It is found that the width of the cross-correlation function increases with travel distance. We interpret the increase in width as the dispersion of the wave packet in a time – distance analysis. The dispersion would also cause a decrease in amplitude and affect the determination of lifetimes. We include the dispersion effect in the determination of lifetimes of high-degree p modes in a time – distance analysis and find that the derived lifetime increases significantly compared with the previous study for degree less than 400. |
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Keywords: | Solar oscillations Helioseismology Waves |
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