Phoebe Spherical Harmonics decomposition

The extent of differentiation of its interior can potentially help inform its formation location because it is mainly determined by heat from 26-aluminium. The internal structure is reflected in the shape, assuming the body is relaxed to hydrostatic equilibrium.

Although previous data analysis indicates Phoebe is close to hydrostatic equilibrium, its heavily cratered surface makes it difficult to tease out its low-order shape characteristics. This paper aims to extract Phoebe's global shape from the observations returned by the Cassini mission for comparison with uniform and stratified interior models under the assumption of hydrostatic equilibrium. The global shape is derived from fitting spherical harmonics and keeping only the low-degree harmonics that represent the shape underneath the heavily cratered surface.