Star clusters in a nuclear star-forming ring: The disappearing string of pearls

Abstract

An analysis of the star cluster population in a low-luminosity early type galaxy, NGC 2328, is presented. The clusters are found in a tight star-forming nuclear spiral/ring pattern and we also identify a bar from structural 2D decomposition. These massive clusters are forming very efficiently in the circum-nuclear environment, they are young, possibly all less than 30 Myr of age. The clusters indicate an azimuthal age gradient, consistent with a "pearls-on-a-string" formation scenario suggesting bar driven gas inflow. The cluster mass function has a robust down-turn at low masses at all age bins. Assuming clusters are born with a power-law distribution, this indicates extremely rapid disruption at time-scales of just several Myr. If found to be typical, it means that clusters born in dense circum-nuclear rings do not survive to become old globular clusters in non-interacting systems.