  We study equilibrium sequences of close binary systems on circular orbits and
composed of different mass stars with polytropic equation of state in Newtonian
gravity. The solving method is a multidomain spectral method which we have
recently developed. The computations are performed for both cases of
synchronized and irrotational binary systems with adiabatic indices $\gamma =
3, 2.5, 2.25, 2$ and 1.8, and for three mass ratios: $M_1/M_2 =0.5, 0.2$ and
0.1. It is found that the equilibrium sequences always terminate at a mass
shedding limit (appearance of a cusp on the surface of the less massive star).
For synchronized binaries, this contrasts with the equal mass case, where the
sequences terminate instead by a contact configuration. Regarding the turning
point of the total angular momentum (or total energy) along a sequence, we find
that it is difficult to get it for small mass ratios. Indeed, we do not find
any turning points for $M_1/M_2 \le 0.5$ in the irrotational case. However, in
the synchronized case, it becomes easier again to find one for mass ratios much
smaller than $M_1/M_2 \sim 0.2$.
