by Paolo Serra (CASS)

The outskirts of galaxies are of paramount importance for the study of galaxy evolution. They are characterised by long dynamical timescales and, therefore, retain a memory of past accretion/merging events for a long time. Unfortunately, they are also challenging to observe because of their vary faint surface brightness. In a recent paper, Duc et al. (2015; including ATNF’s Paolo Serra) present the result of a large observational campaign to study the faint outskirts of early-type galaxies as part of the Atlas3D project. These spectacular images reveal a large number of new features invisible in previous images, such as blue star-forming spiral arms, shells and a large diversity of tidal tails. The animation above shows NGC 5574/76 as seen by SDSS and by the new Atlas3D images obtained using the CFHT telescope.

Credits: Pierre-Alain Duc and Atlas3D team