Assigned ID: 727 ----- Attempting Submission 1 (Fri Feb 26 22:46:02 GMT 2010) ----- We propose to carry out the first comprehensive survey for ultra-compact dwarfs (UCDs) located in all environments from isolated to cluster core. To do this we will analyze archival HST WFPC2 and ACS imaging of 528 galaxies located between 5 and 60 Mpc. This project will build upon a successful pilot archival survey of 76 low-density environment galaxies studied with HST, which has discovered 11 UCD candidates of which 4 have been spectroscopically confirmed as UCDs. By combining structural information from HST imaging with dynamical masses and stellar population parameters from follow-up SALT spectroscopy, we will be able to robustly classify each UCD into one of two categories: massive star clusters (formed by gas-rich major galaxy mergers), or, stripped nuclei (formed by minor mergers). Because many of the target galaxies are located in field/group environments where merger events may be recent and involve star formation, this survey should produce the first significant sample of young UCDs. The population of young UCDs will reveal their intrinsic numbers before losses due to dynamical friction. Our final dataset will provide the frequency of each UCD type as a function of environment, allowing us to measure (1) the dominant formation mechanism of UCDs, and (2) the major and minor merger histories of their host galaxies.

UNRESOLVED STELLAR POPULATIONS AND GALAXY STRUCTURE 12 99665 Budget to be split over two years. false 0.0 0.0 false false false false false false SUPPORTED