NGC7600 is an elliptical galaxy and is around 50 Mpc in distance. This image shows an interleaved system of shells that are described in this Astronomical Journal Letters here. These types of structures around elliptical galaxies were first revealed by Malin & Carter in 1980. This deep image shows faint features not previously seen in color.
This simulation is a full cosmological N-body model based on the "cold dark matter theory". It shows how the continuous accretion of clumps of dark matter and stars creates diffuse structures in the haloes of massive elliptical galaxies. These bare a striking resemblance to the shells observed around the nearby elliptical galaxy NGC 7600. The movie shows close encounters of dark matter haloes that coalesce and oscillate radially about the center of the main galaxy. Along with the debris of smaller dwarf galaxies the mergers establish a main halo were shells propagate outwards. The tidal forces disrupt many of the smaller galaxies leaving behind streams of debris (star streams). Simulation Credits: Andrew Cooper, Carlos Frenk, John Helly, and Shaun Cole. Image of NGC7600 by Ken Crawford in collaboration with David Martinez-Delgado. NGC7600 is inserted into the movie to show the similarity of the model to the observed structures.
This movie has been shortened.