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J.A. Klimchuk (Naval Research Lab), S.E.M. Tanner (George Mason U.), I. De Moortel (U. St. Andrews)
Intensity disturbances have been observed by TRACE and EIT to propagate upward along the legs of long active region coronal loops. The periodic nature and speed of these disturbances suggest that they are traveling acoustic waves. It is being debated, however, whether the damping of the perturbations is consistent with the acoustic wave interpretation. We here examine this issue in detail with a combination of numerical simulation, analytical theory, and improved analysis of the observations. Using our state-of-the-art 1D hydro code, we simulate the propagation of waves generated at the base of model coronal loops. We consider static equilibrium loops having constant and expanding cross-section, and an equilibrium loop with steady flow. We show that the amplitude of the intensity perturbation is affected by a number of factors: wave dissipation (direct plasma heating), work done by the wave on the flow, pressure stratification, nonuniform temperature, and temperature-dependent sensitivity of the observing instrument. We compare our theoretical results with intensity scale lengths measured in a sample of loops observed by TRACE.
Research supported by NASA and ONR.
The author(s) of this abstract have provided an email address for comments about the abstract: klimchuk@nrl.navy.mil
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Bulletin of the American Astronomical Society, 36 #2
© YEAR. The American Astronomical Soceity.