The internal structure of Venus and its global deformation

The Sun exerts tidal forces that deform the planet Venus, from deformation and mass redistribution in its interior, involving variation in the gravity field. The deformation of the planet induced by tidal forcing can be observed with the periodic variations of its gravity field and the Love number k2. The planet’s deformation is linked to its internal structure, most effectively to its density, rigidity and viscosity.  Hence the tidal Love number k₂ can be theoretically estimated  for different planetary models.

The terrestrial planet Venus is reminiscent of the Earth twin planet in size and density, which leads to the assumption that the Earth and Venus have similar internal structures. In this work, the calculation of k₂ is done with ALMA, a Fortran 90 program from Spada [2008] which computes the tidal and load Love numbers using the Post-Widder Laplace inversion formula. With a reference Venus model from Dumoulin et al. [2017], we investigate different parameters of the planet’s layers to calculate its frequency dependent tidal k₂. We apply a random variation of each layer’s parameters within certain boundaries, which allows a statistical analysis of the possible Venus models that fall into the observed data (Mass, Moment of Inertia and k2). We test the effect of different parameters in the Venus model on the k₂ and better understand the different hypotheses for the interior of Venus, as mantle viscosity to core structure (a fluid, solid and part fluid part solid core) .