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 } \leq 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 .