Kinematic studies of ultra-faint dwarfs assume these objects to be in dynamic equilibrium, but conclusions based on this assumption will be incorrect if ultra-faint dwarfs are actually being tidally stripped by the Milky Way. Additionally, the speed and severity of hierarchical merging of small galaxies with larger hosts is an important test of cosmology that requires a knowledge of the kinematic states of the host's dwarf population. In this study, we explore the impact of tidal disruption in the Hercules dwarf, a highly spatially extended ultra-faint dwarf which previous studies have suggested may have evidence of extra-tidal features. We performed time series imaging with the CTIO 4m/DECam to trace the extended structure of this galaxy with RR Lyrae stars. Our imaging covers 3 sq. degrees around Hercules -- significantly larger than previous studies. We report the discovery of five new RR Lyrae candidates, three of which lie outside the dwarf's tidal radius and along its elongated major axis and predicted orbit. This result provides additional evidence that Hercules is being tidally disrupted. This work was supported by NSF AST-1151462.
American Astronomical Society Meeting Abstracts #227
- Pub Date:
- January 2016