Damping of MHD Waves in Quiescent Prominences (P50)
Abstract
The effects of radiative losses due to Newtonian cooling and MHD turbulence have been considered to examine the damping of linear MHD waves in unbounded quiescent prominences. Taking account of isotropic viscosity in the momentum equation and viscous as well as radiation terms in energy equation, we derive a general fifth-order dispersion relation. The analytical solutions of the general dispersion relation have been obtained. It is shown that the damping of magnetoacoustic waves depends on the equilibrium density, magnetic field, temperature, frequency and wave number. The fifth-order general dispersion relation has been solved numerically. We have compared our results with the observations taken from the VTT telescope at Sac Peak. We find that the slow mode waves are mainly affected by radiation but fast mode waves remain unaffected, while noting that both of them are damped due to MHD turbulence. We also find that classical viscosity hardly plays a role in damping the magnetoacoustic waves. The radiative losses give acceptable damping lengths for the slow mode waves for the radiative relaxation times in the range 10 - 103 s. It has been found that for a given value of radiative relaxation time, the high frequency slow mode waves are highly damped. We have also investigated the possible role of MHD turbulence in damping of MHD waves and found that a turbulent viscosity can re-produce the observed damping time and damping length in prominences, especially in PCTR. We find that MHD turbulence alone can explain the damping of magnetoacoustic waves in prominences. From prominence seismology, the values of opacity and turbulent kinematic viscosity have been inferred.
- Publication:
-
2nd UN/NASA Workshop on International Heliophysical Year and Basic Space Science
- Pub Date:
- November 2006
- Bibcode:
- 2006ihy..workE.142S