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Two galaxies merging
These four snapshots are from a high-resolution hydrodynamical simulation done by Patrik Jonsson, Greg Novak, and Joel Primack using Volker Springel’s simulation code GADGET and Patrik Jonsson’sSunrise code to visualize the effects of stellar evolution, dust scattering and absorption of light, and re-radiation of the energy at longer wavelengths. Upper left: galaxies first approach; upper right: they then separate; lower left: gravity brings them back together and their centers merge; lower right: an elliptical galaxy results. Collage created by Nina McCurdy.