Ultra compact dwarfs in the Perseus Cluster: UCD formation via tidal
  stripping
  We present the results of a Keck/DEIMOS survey of Ultra Compact Dwarfs (UCDs)
in the Perseus Cluster core. We confirm cluster membership for 14 UCDs, with
radial velocities ~5300 km s$^{-1}$. Two of these confirmed Perseus UCDs have
extremely blue colours ($B-R < 0.6$ mag), reside in star forming filaments
surrounding NGC 1275, and have likely formed as massive star clusters in the
last ~100 Myr. We also measure a central velocity dispersion of a third, UCD13
($\sigma_0 = 38 \pm 8$ km s$^{-1}$), the most extended UCD in our sample. We
determine it to have radius $R_{e} = 85 \pm 1.1$ pc, a dynamical mass of ($2.3
\pm 0.8)\times10^{8}$ M$_{\odot}$, and a metallicity [Z/H]$=
-0.52^{+0.33}_{-0.29}$ dex. UCD13 and the cluster's central galaxy, NGC 1275,
have a projected separation of 30 kpc and a radial velocity difference of ~20
km s$^{-1}$. Based on its size, red colour, internal velocity dispersion,
dynamical mass, metallicity and proximity to NGC 1275, we argue that UCD13 is
likely the remnant nucleus of a tidally stripped dE, with this progenitor dE
having $M_{B} \approx -16$ mag and mass $\sim10^{9}$ M$_{\odot}$.
