RUBIS: A simple tool for calculating the centrifugal deformation of stars and planets

Abstract

Aims. We present the Rotation code Using Barotropy conservation over Isopotential Surfaces (RUBIS), a fully Python-based centrifugal deformation program that is available publicly. The code has been designed to calculate the centrifugal deformation of stars and planets resulting from a given cylindrical rotation profile, starting from a spherically symmetric non-rotating model. Methods. The underlying assumption in RUBIS is that the relation between density and pressure is preserved during the deformation process. This leads to many procedural simplifications. For instance, RUBIS only needs to solve Poissona's equation in either spheroidal or spherical coordinates, depending on whether the 1D model has discontinuities. Results. We present the benefits of using RUBIS to deform polytropic models and more complex barotropic structures, thus providing insights into baroclinic models to a certain extent. The resulting structures can be used for a wide range of applications, including the seismic study of models. Finally, we illustrate how RUBIS is beneficial specifically in the analysis of Jupitera's gravitational moments through its ability to handle discontinuous models while retaining a high accuracy compared to current methods.