Seismic wavefields in a planet and their influence on the satellite orbit

Seismology can play an important role in both astronomy and planetary science. We will mainly discuss the recently proposed Tidal-Seismic Resonance (TSR) effect and its role on the orbital evolution of the moon around a planet. For a planet-moon system, TSR is expected when a tidal force frequency matches a free-oscillation frequency of the planet. TSR can excite large-amplitude seismic waves that can change the shape of the planet, which in turn, exerts a negative torque on the moon to cause it to fall rapidly toward the planet. We have developed a 3-D seismic wavefield modeling package, AstroSeis, to numerically study the moon's orbit change. We further speculate that TSR might be an important mechanism to accelerate the planet accretion process in the early history of star formation. Because TSR significantly depends on the seismic Q value and S-wave velocity of the planet when its size was still small, future work studying the seismic wave velocity and Q of some asteroids in micro-gravity environments is important to reveal the evolution history of planets and the solar system.