Problems of Solar and Stellar Oscillations

D. O. GOUGH Institute of Astronomy. Madingley Road. Cambridge. U. K. IAU Colloquium 66 on 'Problems of Solar and Stellar Oscillations' was held at the Crimean Astrophysical Observatory, U. S. S. R. , on 1-5 September, 1981. The principal purpose of the colloquium was to study the low-amplitude oscillations of the Sun and, to a lesser extent, to consider similar oscillations of other stars. Much of the emphasis of the discussions was on the diagnostic value of the oscilla­ tions. In the last few years we have become aware that the frequencies of the five-minute modes of high degree, which constitute the major component of the oscillations discovered twenty years ago by Evans and Michaud, can be used to put quite tight bounds on the stratification of the solar convection zone. These permit a calibration of solar models computed from so-called standard evolution theory. Modes of low degree penetrate beneath the convection zone to the core of the Sun, and can in principle test the evolution theory. Therefore there was considerable interest in the reports of the latest observations of such modes. Broadly speaking, those observations confirm the cali­ bration by the high-degree modes, but there remain some systematic discrepancies that demand some revision of the theory. Besides the gross aspects of evolution theory, there are also more intricate details to be understood.

Foreword.- Manifestation of the 160-min Solar Oscillations in Velocity and Brightness (Optical and Radio Observations) (Invited Review).- Observation of Global 160-min Infrared (Differential) Intensity Variation of the Sun.- Structure of the Solar Oscil lation with Period near 160 Minutes.- The Measurement of Long-Period Oscillations at Sacramento Peak Observatory and South Pole.- Full-Disk Observations of Solar Oscillations from the Geographic South Pole: Latest Results (Invited Review)..- Solar Oscillations Observed in the Total Irradiance.- Detection of Solar Five-Minute Oscillations of Low Degree.- Detection of Individual Normal Modes of Oscillation of the Sun in the Period Range from 2 hr to 10 min in Solar Diameter Studies.- Helioseismology with High Degree p-Modes (Invited Review).- Recent Observations of High-Degree Solar p-Mode Oscillations at the Kitt Peak National Observatory (Invited Review, Abstract).- Statistical Considerations in the Analysis of Solar Oscillation Data by the Superposed Epoch Method.- On the Accuracy of Frequency Determination by an Autoregressive Spectral Estimator.- On the Origin of Oscillations in a Solar Diameter Observed through the Earth’s Atmosphere: A Terrestrial Atmospheric or a Solar Phenomenon.- Solar Diameter(s).- Short-Period Oscillations.- Spectral-Spatial Analysis of Wave Motions in the Region of the Temperature Minimum of the Sun’s Atmosphere.- Observation of Five-Minute-Period Gravity Waves in the Solar Photosphere (Invited Review, Abstract).- Radiative Transfer and Solar Oscillations (Invited Review).- A New Method for Determining the Helium Abundance in the Solar Atmosphere (Invited Review).- 160-min Oscillations of the Sun as a Means of Studying of Its Internal Structure.- Adiabatic Oscillations of Solar Models with a High-Z Convective Zone.- Solar Models with Low Opacity.- Theoretical Eigenfrequencies of Solar Oscillations of Low Harmonic Degree l in Five-Minute Range (Invited Review, Abstract).- Rotational Splitting of Solar Five-Minute Oscillations of Low Degree (Invited Review, Abstract).- Is There an Oblique Magnetic Rotator Inside the Sun? (Invited Review, Abstract).- The Study of Velocity Oscillations in the Solar Photosphere Using the Velocity Subtraction Technique.- A New System for Observing Solar Oscillations at the Mount Wilson Observatory. I: System Design and Installation.- Resonant Coupling between Solar Gravity Modes (Invited Review).- Derivation of the Amplitude Equations of Acoustic Modes of an Unstable Semi-Infinite Polytrope (Invited Review).- Kolmogorov Unstable Stellar Oscillations.- On the Exitation of Oscillations of the Sun (Numerical Models).- A Convenient Method to Obtain Stellar Eigen frequencies.- On the Influence of Nonlinearities on the Eigenfrequencies of Five-Minute Oscillations of the Sun.- On Waves in Non-Isothermal, Compressible, Ionized and Viscous Atmospheres.- Seismology of Sunspot Atmospheres.- Adiabatic Oscillations of a Differentially Rotating Star. Second-Order Perturbation Theory.- Excitation of the Solar Oscillations by Objects Consisting of y-Matter.- Nonlinear Anelastic Modal Theory for Solar Convection (Invited Review).- On the Detection of Subphotospheric Convective Velocities and Temperature Fluctuations.- Variability in the Power Spectrum of Solar Five-Minute Oscillations (Invited Review).- Maunder Convection Mode on the Sun and Long Solar Activity Minima.- Torsional Oscillations of the Sun (Invited Review, Abstract).- Evidence for the Phi-Dependent Rotation-Oscillation of the Sun (and for the Driving Mechanism of the Asymmetric Dynamo).- The Observations of 80-min Oscillations in the Quiescent Prominences.- Atmospheric Internal Gravity Waves as a Source of Quasiperiodic Variations of the Cosmic Ray Secondary Component and their Likely Solar Origin (Invited Review).- 160-min Pulsations in the Magnetosphere of the Earth Possibly Caused by Oscillations of the Sun.- An Essay on Stellar Oscillations and Evolution.- Stellar 5 min Oscillations.- Helioseismology in the Future (Invited Review).