Program: GS-2014A-Q-30

Circumstantial evidence hints that UCDs are a mixed population, composed of objects formed in a manner similar to GCs during the major epochs of star formation, plus a second population consisting of the remnant nuclei left after the stripping of companion galaxies during minor mergers. Conclusive evidence of this scenario has proved elusive, in part because the majority of UCDs studied to date reside in galaxy cluster environments, where the uniformly old nature of the stellar populations makes it difficult to separate objects formed by the two routes. In the first half of this project we used GMOS spectroscopy of the GCs and UCDs of the group elliptical NGC3923 to prove definitively that the multiple UCDs of NGC3923 are of the GC type. We propose to complete this study by confirming the recent stripping origin of a young UCD located around the field S0 NGC4546. To do this we will spectroscopically study the GCs of NGC4546. By comparing the stellar populations of the GCs with those measured for the NGC4546 UCD we will be able to determine unambiguously whether this UCD is the first example of a stripped nucleus type UCD.