Problems in helioseismology

The resonant frequencies of solar acoustic-gravity waves are considered as probes of the sun's internal structure and dynamics. A perturbation method for calculating the effects of slow rotation and weak magnetic fields on p-mode frequencies is presented. Distortion of the equilibrium state of the star is taken into account. The method is applied to various hypothetical magnetic field geometries and rotation laws. Asymptotic estimates are developed and compared with the numerical results. The combined effect of rotation and magnetic fields is discussed. Current observations are reviewed in the light of the present results. A simple model is used to investigate the frequencies of high-degree acoustic modes which may be confined to the solar chromosphere. Such modes may be detected in observations from space. It is argued that they could provide a means of determining the mean sound speed in the chromosphere and the location of the transition zone between chromosphere and corona. It has been suggested that the sun could contain in its core quark nuggets which may constitute the ''missing mass''. Solar oscillations provide an extra set of constraints that any solar model must satisfy. Non-standard solar models containing a central black hole and a quark nugget core are constructed. The effect on a combination of resonant p-frequencies sensitive to conditions in the core is calculated by an asymptotic method. A black hole tends to make agreement between theoretical eigenfrequencies and observation worse. A quark nugget core may improve the agreement but tends to make the neutrino problem more acute. (author)