Spectral darkening functions of solar p-modes - An effective tool for helioseismology

Darkening functions (contrasts) of intensity fluctuations due to waves in a nongrey LTE model of the solar atmosphere are calculated for different wavelengths lambda in the optical continuum spectrum. Adiabatic and isothermal acoustic waves as well as temperature waves are considered. A change of the sign of the darkening function for certain ranges of lambda is revealed for adiabatic waves. This effect makes it possible to observe modes with I greater than or similar to 3 even in stars. Observations of the darkening function of p-modes at different lambda are proposed as a new tool, making it possible. to check numerical models of p-modes, to impose restraints to the choice of the boundary conditions, to reduce the arbitrariness in the calculation of nonadiabatic corrections to eigenfrequencies, and to improve the accuracy of solar interior sounding in this way.