The Disturbed and Globular-cluster-rich Ultradiffuse Galaxy UGC 9050-Dw1

We investigate the ultradiffuse galaxy (UDG) UGC 9050-Dw1, which was selected because of its disturbed morphology as part of a larger sample of UDGs that display evidence for significant interactions. We use the Hubble Space Telescope's Advanced Camera for Surveys to identify globular clusters (GCs) associated with UGC 9050-Dw1, and the Jansky Very Large Array to measure its H I content. UGC 9050-Dw1, a neighbor to the low surface brightness spiral UGC 9050, exhibits a unique UV-bright central "clump" with clearly associated H I gas and an extended stellar tidal plume to the north. We identify 52 ± 12 GCs, implying a specific frequency of S <SUB>N</SUB> = 122 ± 38, one of the highest reported for a UDG of this luminosity ( $\mathrm{log}{L}_{V}/{L}_{\odot }=7.5\pm 0.1$ ). Additionally, ~20% of the total light of the galaxy is contributed by GCs. Nearly uniform GC colors suggest they were formed during a single intense episode of star formation. We posit that UGC 9050-Dw1 represents the initial definitive observational example of UDG formation resulting from a dwarf merger event, where subsequent clumpy star formation has contributed to its present observed characteristics.