Galaxy cluster
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A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to
Composite image of BoRG-58, a group of 5 galaxies clustered together just 600 million years after the Universe's birth
Galaxy cluster IDCS J1426 is located 10 billion light-years from Earth and has the mass of almost 500 trillion suns (multi-wavelength image: X-rays in blue, visible light in green, and infrared light in red).
Abell 2744 galaxy cluster – extremely distant galaxies revealed by gravitational lensing (16 October 2014).
Galaxy cluster SPT-CL J0615-5746.
Galaxy group
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A galaxy group or group of galaxies is an aggregation of galaxies comprising about 50 or fewer gravitationally bound members, each at least as luminous as the Milky Way ; collections of galaxies large
Four of the seven members of galaxy group HCG 16