A Photometric and Kinematic Analysis of UDG1137+16 (dw1137+16): Probing
  Ultra-Diffuse Galaxy Formation in a Group Environment
  The dominant physical formation mechanism(s) for ultra-diffuse galaxies
(UDGs) is still poorly understood. Here, we combine new, deep imaging from the
Jeanne Rich Telescope with deep integral field spectroscopy from the Keck II
telescope to investigate the formation of UDG1137+16 (dw1137+16). Our new
analyses confirm both its environmental association with the low density UGC
6594 group, along with its large size of 3.3 kpc and status as a UDG. The new
imaging reveals two distinct stellar components for UDG1137+16, indicating that
a central stellar body is surrounded by an outer stellar envelope undergoing
tidal interaction. Both the components have approximately similar stellar
masses. From our integral field spectroscopy we measure a stellar velocity
dispersion within the half-light radius (15 $\pm$ 4 $\mathrm{km\ s^{-1}}$) and
find that UDG1137+16 is similar to some other UDGs in that it is likely dark
matter dominated. Incorporating literature measurements, we also examine the
current state of UDG observational kinematics. Placing these data on the
central stellar velocity dispersion -- stellar mass relation, we suggest there
is little evidence for UDG1137+16 being created through a strong tidal
interaction. Finally, we investigate the constraining power current dynamical
mass estimates (from stellar and globular cluster velocity dispersions) have on
the total halo mass of UDGs. As most are measured within the half-light radius,
they are unable to accurately constrain UDG total halo masses.
