Dynamics of the globular cluster M 2 (NGC 7089).
Abstract
Radial velocities have been obtained for 69 stars in the globular cluster M2 (NGC 7089). M2's rotation axis is, within sizeable uncertainties, perpendicular to the major axis determined by the flattening. The ratio of rotational to random kinetic energy agrees with that predicted from the ellipticity, assuming an oblate figure and an isotropic velocitydispersion tensor. KingMichie models have been fitted to determine M2's mass, the exponent of an assumed powerlaw mass function, and the anisotropy radius. The most significant sources of uncertainty in the modeling are the velocity dispersion, the distance, and the massluminosity relation for the cluster stars. The models favor mass functions similar to or shallower than the Salpeter initialmass function and a moderate amount of velocity anisotropy.
 Publication:

The Astronomical Journal
 Pub Date:
 March 1986
 DOI:
 10.1086/114035
 Bibcode:
 1986AJ.....91..546P
 Keywords:

 Celestial Mechanics;
 Globular Clusters;
 Stellar Motions;
 Astronomical Models;
 Distance;
 Luminosity;
 Mass To Light Ratios;
 Radial Velocity;
 Astrophysics