Isolated compact elliptical galaxies: Stellar systems that ran away
  Compact elliptical galaxies form a rare class of stellar system (~30
presently known) characterized by high stellar densities and small sizes and
often harboring metal-rich stars. They were thought to form through tidal
stripping of massive progenitors, until two isolated objects were discovered
where massive galaxies performing the stripping could not be identified. By
mining astronomical survey data, we have now found 195 compact elliptical
galaxies in all types of environment. They all share similar dynamical and
stellar population properties. Dynamical analysis for nonisolated galaxies
demonstrates the feasibility of their ejection from host clusters and groups by
three-body encounters, which is in agreement with numerical simulations. Hence,
isolated compact elliptical and isolated quiescent dwarf galaxies are tidally
stripped systems that ran away from their hosts.
