The Stellar Dynamics of M87

We extract the shape of the stellar velocity ellipsoid as a function of radius in M87 from van der Marel's (1994) velocity dispersion data. We include the gravitational force of a central black hole with the mass quoted by \cite{har94}. The kinematical data are corrected for the effects of seeing and instrumental blurring using a nonparametric algorithm. We find that the stellar motions in M87 are slightly radially anisotropic throughout the main body of the galaxy, with sigma_r ~ 1.2 sigma_t . However sigma_t exceeds sigma_r within the inner 1''-2'' by a statistically significant amount. A number of models for the formation of nuclear black holes predict a tangential anisotropy in the stellar motions, and our results provide evidence for such an effect in M87.