  Compact elliptical galaxies are characterized by small sizes and high stellar
densities. They are thought to form through tidal stripping of massive
progenitors. However, only a handful of them were known, preventing us from
understanding the role played by this mechanism in galaxy evolution. We present
a population of 21 compact elliptical galaxies gathered with the Virtual
Observatory. Follow-up spectroscopy and data mining, using high-resolution
images and large databases, show that all the galaxies exhibit old metal-rich
stellar populations different from those of dwarf elliptical galaxies of
similar masses but similar to those of more massive early-type galaxies,
supporting the tidal stripping scenario. Their internal properties are
reproduced by numerical simulations, which result in compact dynamically hot
remnants resembling the galaxies in our sample.
