Publication Date

Fall 2016

Degree Type


Degree Name

Master of Science (MS)


Physics and Astronomy


Aaron J. Romanowsky


dwarf spiral galaxy, globular cluster, NGC 247, Subaru Hyper Suprime-Cam, ultra compact dwarf

Subject Areas

Physics; Astronomy


While globular clusters (GCs) are among the most ancient stellar systems in the universe, there are still lingering questions about how and where they formed. There is relatively little known about GCs in spiral galaxies beyond the Milky Way. We analyzed confirmed GCs, examined putative GC candidates, and looked for new GCs around the nearby dwarf spiral galaxy NGC 247 at about 3.5 Mpc away in the Sculptor group, based on wide-field imaging data from the Subaru Hyper Suprime-Cam (HSC), with a 1.5 degree field of view. The extremely wide-area coverage, depth, and image quality of HSC provide great potential for studying GCs around nearby galaxies. Using colors, magnitudes, and sizes of spectroscopically-confirmed objects, we defined criteria for selecting GC candidates in NGC 247. We examined candidates visually and were able to eliminate objects that were previously classified to be GC candidates, as well as find new GC candidates. Spectroscopic follow-up is planned to confirm some of the new GC candidates.