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Constraints on a MOND effect for isolated aspherical systems in deep Newtonian regime from orbital motions

Non-spherical systems described by MOND theories of modified gravity arising from generalizations of the Poisson equations are affected by a MONDian extra-quadrupolar potential ϕ_M even if they are isolated and they are in deep Newtonian regime. In general MOND theories quickly approaching Newtonian dynamics for accelerations beyond A_0, ϕ_M is proportional to a multiplicative scaling coefficient α\sim 1, while in MOND models becoming Newtonian beyond κA_0, κ>> 1, it is enhanced by κ^2. We analytically work out some orbital effects due to ϕ_M in the framework of QUMOND, and compare them with the latest observational determinations of Solar System&#39;s planetary dynamics, exoplanets and double lined spectroscopic binary stars. The current admissible range for the anomalous perihelion precession of Saturn yields |κ| <= 3.5 x 10^3, while the radial velocity of αCen AB allows to infer |κ|<= 6.2 x 10^4 (A) and |κ|<= 4.2 x 10^4 (B). In evaluating such preliminary constraints it must be recalled that QUMOND is not the nonrelativistic limit of TeVeS.