Predicted values of the Yarkovsky effect and the density for asteroid (85989) 1999 JD6. Bottom panel: Predicted semimajor axis drift da/dt (ordinate) due to the Yarkovsky effect from our model for three different values of the bulk density (1.5, 2, and 2.5 g cm⁻³; see the labels) shown by the solid curves; the abscissa is the surface thermal inertia in SI units (Jm⁻² s^−0.5 K⁻¹). We assumed the rotation state and shape model from the light-curve inversion in Sect. 2.3 and an effective size of 1.45 km. The grayscale horizontal region shows the value −(4.26 ± 0.98) × 10⁻⁴ au My⁻¹ from the orbit determination. Top panel: Model-predicted bulk density to match the observed value of the semi-major axis drift shown by the grayscale region. The solid line in the middle shows the exact correspondence surrounded by a map of the sigma interval of the Yarkovsky drift. The nominal effective size of 1 km is used. If this value were lower or higher, the density solution would shift in the direction indicated by the arrows (preserving the p_b D value). The analysis of ten different shape models of (85989) 1999 JD6 reveals a variation of ±10% about the median value used in the figure.