(a′–c′) dimension of (65) Cybele as a function of density (top cyan circle). The polar oblateness of the asteroid is close to the expected values for a homogeneous body with a similar rotation period (black line). The expected oblateness of bodies with increasingly differentiated interiors (‘X’ symbols) gradually depart from the measured value. A highly differentiated interior (plus symbol) is unlikely, unless Cybele’s rotation state significantly changed after it acquired its shape. Considering the flattening of the north pole of Cybele, we also computed best-fit ellipsoids obtained by fitting the southern pole of the 3D model only. The resulting (a′–c′) dimensions for fits up to planetocentric latitudes of 20° south and 35° south are shown by the middle blue and bottom light-blue circles.