The empty ring galaxy ESO 474-G040

Abstract

We describe observations of the apparently empty ring galaxy ESO 474-G040 obtained with the Southern African Large Telescope. The observations, consisting of imaging, long-slit spectroscopy and Fabry-Pérot mapping of the H α line, allow determining the ring kinematics as well as estimating the metallicity of the ring and the stellar population composition in its various parts. We propose that the object could best be understood as being the result of a past merger of disc galaxies, which formed a gas ring that subsequently disrupted via the bead instability and is presently forming stars.