Thermal and Mechanical Damping of Solar pModes
Abstract
Nonadiabatic effects associated with the transfer of energy and with turbulent stresses add small imaginary parts, omegai(1) and omegai(2), to solar pmode eigenfrequencies. Numerical calculations have shown that these quite different processes make comparable contributions to omegai at frequencies well below the acoustic cutoff at omegaac. Analytic expressions are derived which reveal the connection between omegai(1) and omegai(2). The estimates yield omegai proportional to omega exp 8 for omega much less than omegaac in good agreement with the numerical calculations. However, the observed line width is proportional to omega exp 4.2 at low frequencies. It is suspected that there is an unmodeled component of perturbed convective energy transport or of turbulent viscosity that makes an important contribution to omegai at omega much less than omegaac.
 Publication:

The Astrophysical Journal
 Pub Date:
 June 1991
 DOI:
 10.1086/170126
 Bibcode:
 1991ApJ...374..366G
 Keywords:

 Damping;
 Radiative Transfer;
 Solar Oscillations;
 Photosphere;
 Sound Waves;
 Spectral Line Width;
 Solar Physics;
 RADIATIVE TRANSFER;
 SUN: OSCILLATIONS;
 TURBULENCE