The free oscillations of Jupiter

The spectrum of free oscillations of Jupiter is calculated for a set of models, each of them fitting all available observational data. Diagnostic capabilities of the spectrum are studied. They could be used, as soon as relevant observations are performed, for both the identification of the observed modes and the improvement of the models themselves. The calculations were made for five-layer models. They differ in the core mass (2–10 M⊕) and in the molecular-metallic phase transition pressure of hydrogen (1.5–3 Mbar). The spectrum of Jupiter consists of gravitational modes related to density jumps in the planetary interiors and of acoustic modes. The periods of the acoustic modes are calculated for degree up to l=30 and overtone number up to n=20. The investigated models have a characteristic frequency of ≈152–155 μHz. Two outer gravitational modes related to density jumps in the molecular envelope and at the interface with the metallic envelope have nonzero displacements at the planetary surface. These modes have good diagnostic properties. The values of the kinetic energy averaged over the period of oscillation are calculated for a 1-m amplitude of the displacement at the planetary surface. The influence of all effects of rotation on the spectrum is discussed.