Observational tests in scale invariance III: wide binary stars

Recent studies of wide binary stars based on Gaia DR3 suggest that the relative orbital velocities of objects with separations s > 3'000 astronomical units are statistically larger than the standard Newtonian predictions. Obviously there is no Dark Matter halo arround binary stars that could be invoked to explain these high velocities. However, we explore the properties of two-body systems in the framework of scale invariant vacuum theory, focusing on the case of objects with extreme separations. In this regime, the additional acceleration term present in the modified Newton equation with scale invariance becomes important, and may even dominate the dynamical evolution at very low gravities. Comparisons with Gaia DR3 observations of wide binaries are performed and suggest that binaries with separations s > 3'000 astronomical units have experienced such an evolution for a few Gyr, accounting well for the observed velocity excesses.