Stephan's Quintet

Common card · No. 248095

Stephan's Quintet is a visual grouping of five galaxies in the constellation Pegasus, four of which form a physical association, known as the Hickson Compact Group 92. It was the first compact galaxy group to be discovered and one of the most heavily studied compact galaxy groups. The group was discovered by Édouard Stephan in 1877 using the 80 cm reflector telescope at the Marseille Observatory. The brightest member of the apparent grouping, NGC 7320, while the brightest member of the physical association is NGC 7318B. Radio observations in the late 1970s revealed a filament of emission between the galaxies in the group. Subsequent observations with space telescopes identified the filament as a shock wave in the intragroup gas, caused by the high-speed collision of the new intruder (NGC 7318B) with the intragroup medium at approximately 850–1,000 km/s. The shock created several observable phenomena across the electromagnetic spectrum and has been proposed to have triggered the active galactic...

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