Using the Hubble Space Telescope (HST), astronomers from the University of California Santa Cruz (UCSC) and elsewhere have observed an ultra-diffuse galaxy known as FCC 224. Results of the observational campaign, published Jan. 18 on the arXiv pre-print server, provide important insights into the properties of this galaxy and its globular cluster system.

Globular clusters (GCs) are collections of tightly bound stars orbiting galaxies. Astronomers perceive them as natural laboratories enabling studies on the evolution of stars and galaxies. In particular, GCs could help researchers to better understand the formation history and evolution of early-type galaxies, as the origin of GCs seems to be closely linked to periods of intense star formation.

Located some 65 million light years away in the Fornax galaxy cluster, FCC 224 is a quiescent ultra-diffuse galaxy about 10 billion years old. It has a major axis effective radius of approximately 6,160 light years and its mass is estimated to be at a level of 200 million solar masses.