RADII, STRUCTURE, AND ORBITS OF GLOBULAR-CLUSTERS

Galactic globular clusters, that do not have collapsed cores, are found to exhibit a well defined correlation between luminosity and central concentration of light. Available observations tentatively suggest that globulars in the Large Cloud, and perhaps in M31 obey similar relationships. Galactic globular clusters on nearly circular orbits are seen to be systematically larger than other globulars (>99% confidence). Clusters on retrograde orbits are systematically smaller than other globulars. Globular clusters in the outer halo of the Galaxy and in the halo of the Magellanic Clouds have very large radii. The observation that globulars in the Fornax dwarf are smaller than those in the outer halo of the Galaxy, and that carbon stars are rare in the halo, suggests that the bulk of outer halo of the Galaxy may not have formed by the disintegration of dwarf spheroidal galaxies. Implications of the present results for ideas on the formation of (baryonic) galactic halos are briefly discussed.