MASSES OF STAR CLUSTERS IN THE NUCLEI OF BULGELESS SPIRAL GALAXIES

In the last decade star clusters have been found in the centers of spiral galaxies across all Hubble types. We here present a spectroscopic study of the exceptionally bright (10 6 –10 8 L� )butcompact( re � 5 pc) nuclear star clusters in very late type spirals with the Ultraviolet and Visual Echelle Spectrograph at the VLT. We find that the velocity dispersions of the nine clusters in our sample range from 13 to 34 km s � 1 . Using photometric data from the Hubble Space Telescope WFPC2 and spherically symmetric dynamical models, we determine masses between 8 ; 10 5 and 6 ; 10 7 M� . The mass-to-light ratios range from 0.2 to 1.5 in the I band. This indicates a young mean age for most clusters, in agreement with previous studies. Given their high masses and small sizes, we find that nuclear clusters

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