Structure in the Velocity Space of Globular Clusters

Abstract

We present an analysis of the velocity space of a sample of globular clusters (GC) with absolute proper motions. The vertical component of the velocity is found to be correlated with luminosity and galactocentric radius. We divided the sample into two luminosity groups above and below the peak of the luminosity function (LF), MV=-7.5, for Galactic GCs. The two groups display different kinematic behaviour according to the first and second statitical moments of the velocity distribution as well as distinct velocity ellipsoids. The velocity ellipsoid of the high luminosity clusters is aligned with the symmetry axes of the Galaxy, whereas the minor axis of the Low Luminosity group is strongly inclined relative to the Galactic rotation axis.

4 pages, 2 Poscript figures, uses new aa.cls. Astronomy and Astrophysics (Letters) accepted

References in corpus (4)

• Binding Energy and the Fundamental Plane of Globular Clusters
• The Evolution of the Globular Cluster System in a Triaxial Galaxy: Can a Galactic Nucleus Form by Globular Cluster Capture?
• Kinematics of the Galactic Globular Cluster System: New Radial Velocities for Clusters in the Direction of the Inner Galaxy
• The Structure of the Outer Halo of the Galaxy and its Relationship to Nearby Large-Scale Structure