Stephan's Quintet

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{{Galaxy cluster | name = Stephan's Quintet | image = Image:Stephan'sQuintet.jpg NGC 7320, NGC 7319, NGC 7318, NGC 7317
(In clockwise order from 12:00) | type = Compact galaxy group | distance = 300 million | constellation = Pegasus | member_no = 5 | main_member = NGC 7320 | names = HGC 92 }}

Stephan's Quintet is a visual grouping of five galaxies. The group was discovered by Édouard Stephan in 1877 at Marseilles Observatory. The brightest member is NGC 7320 is shown to have extensive H II regions, identified as red blobs, where active star formation is occurring.

More recently known, these galaxies are of interest because of their violent collisions. Four out of the five galaxies in the Stephan Quintent are on a collision course. The NASA Spitzer Space Telescope revealed the presence of a huge intergalactic shock wave, shown by the magnificent green arc in the picture above produced by one galaxy falling into another at millions of miles per hour. As NGC 7318B collides with NGC 7318A, gas spread throughout the cluster, atoms of hydrogen are heated in the shock wave, producing the green glow. The molecular hydrogen seen here is one of the most turbulent forms of molecular hydrogen ever seen. This phenomenon was discovered by an international team of scientists of the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg. Most notable is the fact that this collision can help provide a view into what happened in the early universe 10 billion years ago when it formed.

Also of interest, NGC 7320 indicates a small redshift (760 km/s) while the other four exhibit large redshifts (near 6600 km/s). If redshift correlates with distance, then NGC 7320 may be only a foreground projection and is 32 million ly from Earth versus the 280-340 million ly of the other four.

NGC 7319 has type 2 Seyfert nucleus. Template:Clear

1 Members
2 Other images
3 See also
4 References
5 External links

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Members

Name	Type	Distance Million (ly)	Magnitude
NGC 7317	E2	300	+13.6
NGC 7318 (UGC 12099/100)	E2/SB(s)ab	300	+13.4
NGC 7319	SB(sr)bc	300	+13.3
NGC 7320	SAc	41	+12.6

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Other images

By HST

In infared by SST

Distances between

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References

A Shocking Surprise in Stephan's Quintet. 2 March 2006. 10 March 2006 NASA/JPL-Caltech/Max-Planck Institute/P. Appleton article
P.N. Appleton, K.C. Xu, W. Reach, M.A. Dopita, Y. Gao, N. Lu, C.C. Popescu, J.W. Sulentic, R.J. Tuffs, and M.S. Yun. Powerful High-Velocity Dispersion Molecular Hydrogen Associated with an Intergalactic Shock Wave in Stephan's Quintet, The Astrophysical Journal, 639:L51-L54, 03 March 2006. 10 March 2006 Gigantic cosmic cataclysm in Stephan's Quintet of galaxies
Stephan's Quintet. 10 March 2006 University of Alabama Astronomy
Stephan's Quintet: Intruder Galaxy Shocks Tightly-Knit Group. 8 May 03. 10 March 2006 Chandra X-Ray Observatory

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