Title: Exploring the Globular-Cluster-Ultra-Compact Dwarf Transition

Abstract:  I will present an investigation of individual star clusters by examining the intriguing and poorly understood transition 
region between normal globular clusters and other, more massive compact stellar systems such as ultra-compact dwarfs and 
the dense nuclei of dwarf galaxies.  Evidence involving color, magnitude, and scaling relations involving structural parameters 
and masses, allow ultra-compact dwarfs to be either pure stellar aggregates, similar to globular clusters, or remnant stellar 
nuclei of dwarf elliptical galaxies.  The origin of these objects is therefore quite unclear. Using the environment of the nearby 
giant elliptical galaxy, NGC 5128, we have traced out the properties of its most massive globular clusters.   Using Magellan 
6.5 m + IMACS images, we have measured the structural parameters of over 350 globular clusters in NGC 5128, including the 
most massive clusters.  As well, we have used VLT 8 m + VIMOS spectroscopy to measure the ages, metallicities, and 
alpha-to-iron abundance ratios of 60 ultra-compact dwarf candidates.  With the combination of photometry, structural 
parameters, ages, metallicities, and alpha-to-iron abundance ratios for a large sample of objects within a single galaxy, we 
have one of the best opportunities to reveal the nature of these stellar systems.  I will present our results for the nature of 
massive globular clusters in this galaxy, as well as our estimated impact of local environment on the formation and evolution 
of ultra-compact dwarfs by comparison with dense stellar systems in galaxy clusters.