Some Global Characteristics of the Galactic Globular Cluster System

The relations between the luminosities $M_{V}$, the metallicities $[Fe/H]$,the Galactocentric radii $R$, and the central concentration indices $c$ ofGalactic globular clusters are discussed. It is found that the most luminousclusters rarely have collapsed cores. The reason for this might be that thecore collapse time scales for such populous clusters are greater than the ageof the Galaxy. Among those clusters, for which the structure has not beenmodified by core collapse, there is a correlation between central concentrationand integrated luminosity, in the sense that the most luminous clusters havethe strongest central concentration. The outermost region of the Galaxy with$R>10$ kpc was apparently not able to form metal-rich $([Fe/H]>-1.0)$ globularclusters, whereas such clusters (of which Ter 7 is the prototype) were able toform in some nearby dwarf spheroidal galaxies. It is not yet clear how thepopular hypothesis that globular clusters were initially formed with a singlepower law mass spectrum can be reconciled with the observation that both (1)Galactic globular clusters with $R>80$ kpc, and (2) the globulars associatedwith the Sagittarius dwarf, appear to have bi-modal luminosity functions.Comment: 15 pages, 1 figur