Commission de la Constitution des Etoiles

Abstract

As will be apparent from the Report, notable progress has been accomplished in many directions during the period under review especially in the field of stellar evolution, where some of the most interesting phases are being tackled leading in some cases to the discovery of new forms of instability. Interaction between dynamical instability towards non-radial oscillations and convective instability has been clarified and delicate forms of instabilities in presence of superadiabatic gradients have been explored. Interest in stellar rotation has increased and has brought sometimes unexpected results as the resulting increase of the critical mass of white dwarfs. Neutrino astrophysics raises fascinating questions. Non-linear methods have definitely entered the field of variable star theories. The attack of the supernovae phenomenon takes by and by a quantitative aspect. The fundamentals of magnetohydrodynamics as applied to stellar structure are emerging. A proper theory of stellar convection may still be a long way off but progress is undoubtedly on the way. The discovery of quasi-stellar-sources and the attempts to find an interpretation in terms of very large masses as well as the interest in stars of very high densities have opened a whole new field in the theory of stellar structure where the general relativity terms become important. No doubt, the recent discoveries of cold infrared objects and of concentrated X-ray sources will create new spectacular developments in the activities of our Commission and may already require new sections in the next of its reports to the IAU.