Quintet of Stephan

The Quintette of Stephan is a visual grouping of Galaxie S located in the Constellation of PEGASE, and observed for the first time by the Astronome French Edouard Stephan in 1878. Stephan catalogued it as an aggregate of Nébuleuse S , nobody not imagining at the time they were actually galaxies made up of billion star S and located apart from our clean Milky Way.

Several galaxies among this group of five show signs of violent interactions with distorted forms and long star filaments and gas extending very far from the body from the galaxies. This system is the prototype even small clusters called compact groups .

Members of the group

This group of five galaxies is made up in the beginning of NGC 7317 , NGC 7318a , NGC 7318b , NGC 7319 and NGC 7320 .

Actually, only the first four quoted galaxies (of NGC 7317 to NGC 7319) form really a compact group and are located in the same area of space, their spiral arms and their discs besides being very deformed by the forces of tide. This group would be located at approximately 340 million light-years of the Milky Way.

NGC 7320 as for it is much closer (between 35 and 40 million light-years), its alignment in the line of sight of a terrestrial observer being only fortuitous. The redshift of NGC 7320 is appreciably the same one as that of NGC 7331 and its neighbors, it thus belongs probably to the group of NGC 7331.

On the other hand, NGC 7320c , although being visually a little more with the variation of the group (to approximately 4 minutes of arc of NGC 7320), indeed seems to be located in the same area as the four first, large a tail of tide connecting it to NGC 7319.

Data of observation

Observation

The average magnitude of the galaxies of the Quintet is of approximately +14, it is not thus never visible with the naked eye. Located at approximately 4 north-north-west degrees of the square of PEGASE, it is about an object very run by the astronomers amateurs, a Télescope of at least 200mm of diameter being however necessary to start to distinguish something from interesting.

See too

External bonds

  • Astronomy Picture off the Day (November 13rd, 2000) - the Quintet of Stephan seen by the Space telescope Hubble
  • Astronomy Picture off the Day (August 12th, 2003) - the Quintet of Stephan seen in X-ray by Chandra
  • Xu, C. Kevin: Stephan' S Quintet: In Multi-galaxy Collision (pdf) January 2006.

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