Shapes of large main belt asteroids, deviation from hydrostatic equilibria and geophysical properties.

A recent high-angular resolution imaging survey of 42 large main belt asteroids, with the SPHERE/ZIMPOL instrument of VLT, has provided shape models with unprecedented kilometre accuracy. The aim of this paper is to determine the equilibrium figures of these asteroids from their shape models, in order to define a size limit between dwarf planets and small bodies. Therefore, we quantify the deviation of asteroids from homogeneous hydrostatic equilibria (Maclaurin and Jacobi ellipsoids) using a spherical harmonic analysis and a minimization criterion computation.