Observation of global oscillations of the Sun constitutes a primitive seismology of the solar interior. The frequencies, if correctly identified with definite normal modes of vibration, provide a measure of the average velocity of sound in the interior and thereby of its composition and temperature. Fine structure in the frequencies of nonradial modes may provide information on their character (multiplicity) and on the rotation of the solar interior. Study of the amplitudes and phase fluctuations of the vibrations may clarify the excitation and damping of the vibrations.
After a brief historical review emphasizing global velocity spectroscopy an account is given of the present status of the observations of global oscillations in the range of periods of 3 to 160 rain. Finally the future capabilities of the observational techniques and their resultant potential is discussed. * Proceedings of the 14th ESLAB Symposium on Physics of Solar Variations, 16-19 September 1980, Scheveningen, The Netherlands. ** The contribution ascribed to the Birmingham group (Claverie et al., 1980) in this publication bears no relation to the actual talk given by the author in Tucson in March 1979. That talk concerned the consistency of velocity observations and the apparent decay of the 160 m oscillation between 1974 and 1978. Only a suggestion of the existence of structure in the global 5 m oscillation was made and its interpretation, when fully analyzed, in terms of the work of Iben and Mahaffy (1976) was pointed out privately by the author. All references to that Arizona paper, and to the author in that context in the Hill and Dziembowski reference have no foundation: The Iben and Mahaffy paper was known and understood, and the numerical data to utilize it were not available until shortly before submission (July) of the Claverie et al. (1979) contribution to Nature. Thus e.g. the comments in Nature 278, 685 (1979),
reprinted as an introduction in this volume, concerning the heavy element abundance resulting from the present work had no foundations, for the data had not at that time been analyzed.