Stephan's Quintet is a group of five galaxies that are observed in the constellation of Pegasus in the autumn sky. They were discovered by Édouard Stephan, who was the director of the Marseille Observatory in 1877. All were within a 20' area.
Target | RA | DEC | Magnitude | Size | Classification |
NGC 7317 | 22 35.9 | +33 56.7 | 13.6 | 0.8' x 0.7' | E2 elliptical |
NGC 7318A | 22 35.9 | +33 57.9 | 14.3b | 0.8 x 0.6' | E2 elliptical |
NGC 7318B | 22 36.0 | +33 58.0 | 13.9b | 1.4' x 0.9' | SBb barrel spiral |
NGL 7319 | 22 36.1 | +33 58.6 | 13.1 | 1.5' x 1.1' | SBb barrel spiral |
NGC 7320 | 22 36.1 | +33 56.9 | 13.2 | 2.3' x 1.1' | Sd wide armed spiral |
The red shift for these galaxies shows that they lie at radically different distances away. Four of the galaxies (NGC 7301, 7318A, 7318B AND 7319) appear to be moving away from us at an average of 6,000 km/s, placing them about 270 million light years away, whereas NGC 7320 has a measured red shift of only 800 km/s, indicating it to be about 35 million light years away.
This data and many images of the galaxies show the group of four are more blurred than NGC 7320 which seems to suggest the fifth galaxy is a superimposed foreground object that is not gravitationally linked to the others.
Further data has suggested that NGC 7320 may be gravitationally linked to another galaxy NGC 7321 and that NGC 7318B may be just passing and not gravitationally linked to the other three.
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