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
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