The amplitude modulation of the 160-min solar oscillations

The sinusoidal amplitude modulation of the solar oscillations with a period of 160 min is interpreted in terms of solar rotation. Perturbation theory to a first approximation is used to determine how Coriolis forces affect oscillation frequencies. It is found that the spatial pattern of a composite oscillation made up of an oscillation symmetric about the rotation axis and two traveling waves should display a precession about the solar rotation axis with an angular velocity dependent on solar rotation frequency, the type of oscillation and internal structure. For a quadrupole oscillation such as is proposed for the 160-min oscillation, a precession velocity of one half the solar rotation frequency is obtained which implies that the oscillation crests should cross the solar disk with a 27-d period as is observed