Accoustic wave – gravity wave (asteroseismology )

A wave is generated by a disturbance that a restoring force propagates in its environment. It can be very different according to the process that causes it. For example, the physics which describes the waves created by throwing a stone onto the surface of water (gravity wave) differs from that which underlies the propagation of sound in the air (acoustic sound). In the same way, various mechanisms can disturb the interior of the Earth or a star and thus cause oscillations of different kinds. Asteroseismology studies the internal structure of stars through observation of its oscillation modes. The acoustic-type waves have a restoring force linked to the variation of the pressure that exists inside the star. Gravity waves are subjected to the principle of Archimedes.