Discovery of an isolated compact elliptical galaxy in the field

We present the discovery of an isolated compact elliptical (cE) galaxy, found during a search of SDSS DR7 for cE galaxies, and for which we obtained William Herschel Telescope/ACAM imaging. It is ∼900 kpc distant from its nearest neighbour, has an effective r-band radius of ∼500 pc and a B-band mean surface brightness within its effective radius of 19.75 mag arcsec−1. Serendipitous deep SuprimeCam imaging shows that there is no underlying disc. Its isolated position suggests that there is an alternative channel to the stripping scenario for the formation of compact ellipticals. We also report analysis of recent deeper imaging of the previous candidate free-flying cE, which shows that it is, in fact, a normal dwarf elliptical. Hence, the new cE reported here is the first confirmed isolated cE to be found in the field.