Stephan’s Quintet is a visual grouping of five distant galaxies in the constellation of Pegasus. The group is named after the astronomer Edouard Stephan who first observed and documented the group in 1877. The group is also known by it more formal designation – Hickson Compact Group 92.
Although all five galaxies appear to be located near each other in space, only four are actually in close physical association. NGC 7320, the very blue galaxy at the lower left, is a foreground galaxy and is much closer to us than the rest. Astronomers estimate that NGC 7320 is approximately 40 million light years from earth. The other four, NGC 7319 (upper left), NGC 7318A and NGC 7318B (center) and NGC 7317 (lower right) are much more distant. Estimates of their actual distance range from about 210 to 340 million light years from earth.
Astronomers believe that NGC 7319, NGC 7318A, NGC 7318B and NGC 7317 will all eventually merge into each other. Evidence of their close interactions is seen in their distorted shapes.
Also note that NGC 7319, NGC 7318A, NGC 7318B, and NGC 7317 are all much redder than the foreground galaxy NGC 7320, which indicates that they are much older than NGC 7320. Astronomers believe that NGC 7320 was going through an intense phase of star formation at the time the light captured in these images left that galaxy 40 million years ago.
This image was created from Hubble Telescope observations taken in 2009. The composite image was created from filtered data that isolated light from the infrared, green and blue portions of the spectrum and then mapped to red, green and blue respectively.
The data used to create this image is available from the Hubble Legacy Archive page. I used the calibrated and aligned data from the F814W, F606W and F438W filters. Additional data from the hydrogen-alpha narrow band filters was available in the data set but I chose not to use it because of the quality of the data. The data was combined in PixInsight using the following color map scheme –> F814W – red, F606W – green, and F438W – blue. The channels were balanced and histogram stretched in PixInsight and then converted to 16 bit TIFF files for export to Photoshop for touch-up work. There were quite a bit of defects in the data so this image took a bit of Photoshop work to get rid of the lens flares and noise.
Click on the image below to see a larger version. Follow this link to my Astrobin page for a 3000 x 3000 pixel version.