F-P observations of globular clusters

For 47 Tuc, NGC 6397, and M15, the amplitude of the projected rotation measured at a radius of 0.6' using the individual stellar velocities is equal to, or smaller than, that measured at a radius of 0.2' using the integrated light. This is not consistent with the solid-body rotation usually assumed for the inner regions. To study further the form of the projected rotation we have used two-dimensional spline smoothing to derive a mean velocity map for 47 Tuc using the individual stellar velocities.

This map shows that the projected rotation velocity reaches a plateau at a radius of 3' and that the radial dependence of the projected rotation velocity deviates significantly from solid body beyond 2'. We have repeat measurements of the two "high-velocity" stars of Meylan, Dubath, and Mayor. However, we detect more stars with similar large offsets from the cluster mean velocity.

The number of stars that we measure with large velocity offsets is consistent with a normal distribution, so that there is no need to invoke a special creation mechanism for these stars.