Frame Dragging at the Galactic Centre: Lense-Thirring Timescales for the S-Stars

If Sagittarius A* rotates, spacetime near it is dragged around with it, and the orbits of its stars should slowly twist in response. This paper computes how slowly. For the star S2, the Lense-Thirring nodal advance at maximal spin is 6.7 arcseconds per orbit, a fraction 0.0092 of the Schwarzschild advance on the same orbit, accumulating to a full nodal circuit in 3.1 million years; at half-maximal spin the circuit takes 6.2 million years. Per century the maximal effect is 42 arcseconds of orbital-plane twist, far below present astrometric reach on S2 itself, which is why attention has turned to hypothetical closer stars, for which the same formulae give dramatically larger effects. The dimensionless small parameter controlling everything is the ratio of the gravitational radius to the semi-latus rectum, here 1.88e-04. Computed from published orbital elements across a stated spin grid; the spin of Sagittarius A* is not measured here.