THE INFLUENCE OF TURBULENCE ON THE SOLAR P-MODE FREQUENCIES .1. FREE-MODE APPROXIMATION

The influence of turbulence an the frequencies of free acoustic modes in convection zones is considered. The frequencies are modified via th e speed of sound by the turbulence-induced alterations of the effectiv e pressure: (i) by the correlated fluctuations of temperature and dens ity and (ii) the pressure part of the Reynolds stress. The two effects shift the frequency of low I p-modes in opposite directions. In addit ion, the correlation of the density fluctuations with the random veloc ity - the eddy-mass flow - is also relevant. It is, in a steady state, balanced by a vertical mean velocity. The balance results in a rather small net effect completely disappearing for highly nonradial oscilla tions. Both effects of the density fluctuations produce a redshift of the low I p-mode frequencies. The Reynolds stress, however, makes a bl ueshift of the frequencies relative to that computed for a laminar gas . This effect dominates for subsonic turbulences. The applied second-o rder correlation-approximation, however, only holds for the lowest fre quencies, where the KORONAS (solar minimum) data are indicating a blue shift. Of particular importance for the present concept is the expecte d cycle-variations of the lineshifts, i.e. the consideration of the ma gnetic modification of the various contributions. Observations may sho w whether the suggested modifications of the solar oscillation theory are correct.