Nuclear star clusters in late-type spirals

I will summarize the results of our recently completed HST/WFPC2 I-band survey of a sample of 77 nearby, late-type spiral galaxies with low inclination. The main purpose of this catalog is to study the frequency and properties of nuclear star clusters in this class of galaxies. We find that at least 75% of late-type spirals harbor a distinct, compact (but resolved), and dominant star cluster at their photocenter. From an isophotal analysis, we derive the structural and photometric properties of all nuclear clusters in the sample. Based on the luminosity distribution, I will discuss scenarios for their formation history and their possible impact on the evolution of their host galaxies. In addition, I will present first results from follow-up spectroscopy with HST/STIS and VLT/UVES. These and similar observations will reveal the age distribution of nuclear clusters, and will allow to discriminate between competing formation scenarios for nuclear clusters.