The ring was observed in great detail by the Hubble Space Telescope. About 30 star clusters were observed, with masses ranging from 0.5 to over 10 million , fitting the definition of super star clusters. Such massive star clusters have been observed in other starburst and luminous infrared galaxies too. Further examination of the properties of the clusters revealed they group in two populations, a population of intermediate age (∼9–20 Myr) and less obscured (AV ≈ 1 mag) star clusters, accounting for the 75% of the total population, and a population of young (1–3 Myr) and extinct (AV ≈ 3 mag) star clusters. The young stars account for about the one other of the mass of the ring and most of the infrared luminosity. Their location is marked by mid infrared and radio waves peaks, with the two brightest coinciding spatially with the ends of the nuclear molecular gas bar. The total stellar mass of the ring was estimated not to exceed 3.5 × 109 .
