The presence of stars orbiting at the Galactic Center, all placed within an arcsecond distance from the supermassive black hole Sagittarius A*, allow us to test the current theory of gravity outside the Solar System, in an completely different environment from those tested so far.
In this talk I’ll show how the orbital motion of star S2, and specifically the astrometric data collected by GRAVITY, places quite strong constraints on the presence of an hypothetical fifth force, which appears as a Yukawa-like modification to the Newtonian potential. The strongest constraint is found for lambda \sim 10^14 m, for which we found |alpha| < 0.0017 at 95% confidence level, improving by one order of magnitude previous estimates of the same quantity (see Hees et al. 2017). Some future prospects for this work will be also shown.