ON VELOCITY AND INTENSITY LINE ASYMMETRIES

We show that, if solar 5 min. oscillations are excited by convection i n the upper layers of the convective envelope, it is impossible to exp lain the opposite line asymmetries observed in the velocity and intens ity spectra with assumptions on the dissipations which reduce the prob lem to a second order one. The interpretation of that observation requ ires to solve the full nonadiabatic problem which is of the fourth or sixth order. We also analyze the causes of line asymmetries in the fra me of the general problem and we show that to locate the source, it is better to study line asymmetries not too far from line centers.