Hubble Space Telescope Imaging of the Faintest Galaxy, Virgo I

I will present preliminary results from our Hubble Space Telescope follow-up imaging of the faintest candidate dwarf, Virgo I. Virgo I has a Galactocentric radius of approximately 90 kpc and an estimated absolute visual magnitude of -0.8 which makes it the least luminous galaxy discovered to date. This dwarf galaxy could be identified as a prototype "hyper" faint galaxy and give way to a new class of objects. The data from the HST allows us to derive a color-magnitude diagram that is ~3 mag deeper than the Hyper Suprime-Cam discovery data, and thus to assess Virgo I's real nature. The characterization of the smallest inhabited dark matter subhalos is crucial to further our understanding of hierarchal galaxy formation.