An upper limit on the spin of SgrA$^*$ based on stellar orbits in its
  vicinity
  The spin of the massive black hole (BH) at the center of the Milky Way,
SgrA$^*$, has been poorly constrained so far. We place an upper limit on the
spin of SgrA$^*$ based on the spatial distribution of the S-stars, which are
arranged in two almost edge-on disks that are located at a position angle
approximately $\pm 45^\circ$ with respect to the Galactic plane, on a
milliparsec scale around the Galactic Center. Requiring that the frame-dragging
precession has not had enough time to make the S-star orbital angular momentum
precess, the spin of the massive BH at the center of the Milky Way can be
constrained to $\chi\lesssim 0.1$.
