  We apply the Hartle formalism to study equilibrium configurations in the
framework of Newtonian gravity. This approach allows one to study in a simple
manner the properties of the interior gravitational field in the case of static
as well as stationary rotating stars in hydrostatic equilibrium. It is shown
that the gravitational equilibrium conditions reduce to a system of ordinary
differential equations which can be integrated numerically. We derive all the
relevant equations up to the second order in the angular velocity. Moreover, we
find explicitly the total mass, the moment of inertia, the quadrupole moment,
the polar and equatorial radii, and the eccentricity of the rotating body. We
also present the procedure to calculate the gravitational Love number. We test
the formalism in the case of white dwarfs and show its compatibility with the
known results in the literature.
