Stephan's quintet

Stephan's Quintet is a group of five galaxies in the constellation Pegasus , which was discovered on September 22, 1877 by the French astronomer Édouard Jean-Marie Stephan .

The galaxy group consists of the galaxies NGC 7317 , NGC 7318A , NGC 7318B , NGC 7319 and NGC 7320C .

The galaxies NGC 7317 to NGC 7319 form a spatially narrow, interacting system about 300 million light years away. Due to the mutual gravitational effect , the spiral arms of the galaxies are irregularly deformed.

NGC 7320 was originally counted as part of Stephan's quintet by the eponym, but this galaxy is a foreground galaxy in only 35 due to a significantly lower heliocentric radial relative speed (~ 800 km / s compared to ~ 6500–7000 km / s for the other galaxies) Millions of light years away, which only coincides with the projection of Stephan's quintet. Instead, NGC 7320C is now added to the quintet, so that there are still five galaxies.

The galaxies of Stephan's quintet have a brightness of about 13 mag . To observe them, you need a telescope with an opening of at least 20 cm.

Stephen's Quintet and the galaxy NGC 7331 photographed through a 20 cm amateur telescope.
Stephan's quintet. The red rectangle corresponds to the photographed section.
Amateur recording by Stephans Quintet and NGC7331. The image section shown is marked on the location map .