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

TL;DR

This study examines young star clusters in the nuclear ring of galaxy NGC 2328, revealing rapid disruption and a formation pattern driven by bar-induced gas inflow, challenging the survival of such clusters.

Contribution

It provides new insights into the formation and rapid disruption of star clusters in nuclear rings, highlighting the influence of galactic structures like bars.

Findings

Clusters are very young, less than 30 Myr old.

Rapid disruption of clusters occurs within a few Myr.

Clusters do not typically survive to become old globulars.

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.