interacting galaxies

interacting galaxies

Two, three, or (more rarely) four or more galaxies that show signs of mutual disturbance, such as perturbed morphologies or extruded filaments of stellar material, called tidal tails, which can sometimes link to form bridges between the galaxies. Examples include the Antennae, Arp 220 and the Mice. Encounters of galaxies moving at low relative velocities are much more likely to produce mergers than fast encounters, where the interaction time is short and the galaxies pass through each other completely. The infrared satellite IRAS found that many interacting galaxies are powerful infrared sources: the interaction apparently stimulates star formation (see IRAS galaxies). There is also evidence that some radio-quiet QSO lie in interacting galaxies.
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