Oscillations quasi-statiques dans l'atmosphère de η Aquilae

Résumé Fr

The variation with phase of the properties of hydrostatic atmospheric models constructed to interpret the observations of η Aquilae are discussed from the point of view of the theory of pulsations. The lagrangian variations of density combined with the equation of continuity (conservation of mass) yield a distribution of velocity with depth which is compatible with the observations. The conservation of energy is satisfied within the precision of the numerical integrations used. In the case of the equation of motion (conservation of momentum) the problem arises of interpreting the small values of the effective gravity ge adopted in the models. This difficulty which is not bound up with pulsations is discussed at some length. The hypothesis of very strong convection currents arising in the ionization zone of hydrogen and carrying an appreciable net flux of momentum accross the photosphere holds some promise of explaining the weak ge, the atmosphere being then composed of large elements nearly in free fall. The combination of this hypothesis with the theory of pulsations is a delicate problem and a qualitative discussion only is given.