Stephan's Quintet

Galaxy cluster
name = Stephan's Quintet


caption= HGC 92
8-micrometre infrared light = red,
H-alpha = green,
visible red light = blue
epoch = J2000
ra = RA|22|35|57.5cite web
title=NASA/IPAC Extragalactic Database
work=Results for HCG 92
url=http://nedwww.ipac.caltech.edu/
accessdate=2006-09-18]
dec = DEC|+33|57|36
constellation = Pegasus
member_no = 4
brightest_member = NGC 7318B
other_names = HGC 92, Arp 319, VV 288, SQcite journal
author=Moles, M.; Marquez, I.; Sulentic, J. W.
title=The observational status of Stephan's Quintet
journal=Astronomy and Astrophysics,
year=1998
volume=334
pages=473–481
url=http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1998A%26A...334..473M ]

Stephan's Quintet is a visual grouping of five galaxies of which four form the first compact galaxy group ever discovered. The group was discovered by Édouard Stephan in 1877 at Marseilles Observatory.cite journal
author=Stephan, M. E.
title=Nebulæ (new) discovered and observed at the observatory of Marseille, 1876 and 1877, M. Stephan
journal=Monthly Notices of the Royal Astronomical Society
year=1877
volume=37
pages=334–339
url=http://adsabs.harvard.edu/cgi-bin/bib_query?1877MNRAS..37..334S ] The group is the most studied of all the compact galaxy groups. The brightest member of the visual grouping is NGC 7320 that 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 of the five galaxies in Stephan's Quintet are on collision courses with one another. The NASA Spitzer Space Telescope revealed the presence of a huge intergalactic shock wave, shown by the magnificent green arc in the picture to the right produced by one galaxy falling into another at millions of miles per hour. As NGC 7318B collides with NGC 7318A, gas spreads 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 formations 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 postulated beginning of the universe some 14 billion years ago.

Also of interest, NGC 7320 indicates a small redshift (790 km/s) while the other four exhibit large redshifts (near 6600 km/s). Since galactic redshift is proportional to distance, NGC 7320 is only a foreground projection and is ~39 million ly from Earth versus the 210-340 million ly of the other five.

NGC 7319 has type 2 Seyfert nucleus.

Members

=Other

ee also

* Seyfert's Sextet
* Robert's Quartet
* Deer Lick Group

References

* A Shocking Surprise in Stephan's Quintet. 2 March 2006. 10 March 2006 [http://www.spitzer.caltech.edu/Media/releases/ssc2006-08/ 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 [http://www.physorg.com/news11392.html Gigantic cosmic cataclysm in Stephan's Quintet of galaxies]
* Stephan's Quintet. 10 March 2006 [http://www.astr.ua.edu/gifimages/stephan.html University of Alabama Astronomy]
* Stephan's Quintet: Intruder Galaxy Shocks Tightly-Knit Group. 8 May 03. 10 March 2006 [http://chandra.harvard.edu/photo/2003/stephan/ Chandra X-Ray Observatory]

External links

* [http://www.spitzer.caltech.edu/features/articles/20060303.shtml A Shocking Surprise in Stephan's Quintet]
* [http://www.galex.caltech.edu/media/glx2005-02r_img06.html GALEX: Stephan's Quintet and NGC 7331]
* [http://hubblesite.org/newscenter/newsdesk/archive/releases/2001/22/text/ Star Clusters Born in the Wreckage of Cosmic Collisions]
* [http://www.spacetelescope.org/news/html/heic0007.html News Release at ESA/Hubble]
* [http://antwrp.gsfc.nasa.gov/apod/ap001113.html Astronomy Picture of the Day on Stephan's Quintet]
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