Dwarf galaxies in the Perseus Cluster: further evidence for a disc
  origin for dwarf ellipticals
  We present the results of a Keck-ESI spectroscopic study of six dwarf
elliptical (dE) galaxies in the Perseus Cluster core, and confirm two dwarfs as
cluster members for the first time. All six dEs follow the size-magnitude
relation for dE/dSph galaxies. Central velocity dispersions are measured for
three Perseus dwarfs in our sample, and all lie on the $\sigma$-luminosity
relation for early-type, pressure supported systems. We furthermore examine SA
0426-002, a unique dE in our sample with a bar-like morphology surrounded by
low-surface brightness wings/lobes ($\mu_{B} = 27$ mag arcsec$^{-2}$). Given
its morphology, velocity dispersion ($\sigma_{0} = 33.9 \pm 6.1 $ km s$^{-1}$),
velocity relative to the brightest cluster galaxy NGC 1275 (2711 km s$^{-1}$),
size ($R_{e} =2.1 \pm 0.10$ kpc), and Sersic index ($n= 1.2 \pm 0.02$), we
hypothesise the dwarf has morphologically transformed from a low mass disc to
dE via harassment. The low-surface brightness lobes can be explained as a ring
feature, with the bar formation triggered by tidal interactions via speed
encounters with Perseus Cluster members. Alongside spiral structure found in
dEs in Fornax and Virgo, SA 0426-002 provides crucial evidence that a fraction
of bright dEs have a disc infall origin, and are not part of the primordial
cluster population.
