Forward and Inverse Modeling for Jovian Seismology

TL;DR

This paper explores how specific Jovian oscillation modes can be used to infer interior structure details of Jupiter, including discontinuities and core properties, through theoretical modeling and sensitivity analysis.

Contribution

It provides a theoretical framework and sensitivity analysis for using observed Jovian oscillation modes to constrain Jupiter's internal structure and discontinuities.

Findings

Mode set can reliably infer the location of density discontinuities.

Amplitude of sound-speed jumps can be reasonably estimated.

Mode sensitivity allows constraints on core size and mass.

Abstract

Jupiter is expected to pulsate in a spectrum of acoustic modes and recent re-analysis of a spectroscopic time series has identified a regular pattern in the spacing of the frequencies \citep{gaulme2011}. This exciting result can provide constraints on gross Jovian properties and warrants a more in-depth theoretical study of the seismic structure of Jupiter. With current instrumentation, such as the SYMPA instrument \citep{schmider2007} used for the \citet{gaulme2011} analysis, we assume that, at minimum, a set of global frequencies extending up to angular degree $\ell=25$ could be observed. In order to identify which modes would best constrain models of Jupiter's interior and thus help motivate the next generation of observations, we explore the sensitivity of derived parameters to this mode set. Three different models of the Jovian interior are computed and the theoretical pulsation spectrum from these models for $\ell\leq 25$ is obtained. We compute sensitivity kernels and perform linear inversions to infer details of the expected discontinuities in the profiles in the Jovian interior. We find that the amplitude of the sound-speed jump of a few percent in the inner/outer envelope boundary seen in two of the applied models should be reasonably inferred with these particular modes. Near the core boundary where models predict large density discontinuities, the location of such features can be accurately measured, while their amplitudes have more uncertainty. These results suggest that this mode set would be sufficient to infer the radial location and strength of expected discontinuities in Jupiter's interior, and place strong constraints on the core size and mass. We encourage new observations to detect these Jovian oscillations.