Stephan's Quintet

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Stephan's Quintet

HGC 92
8-micrometre infrared light = red,
H-alpha = green,
visible red light = blue
Observation data (Epoch J2000)
Constellation(s) Pegasus
Right ascension 22h 35m 57.5s[1]
Declination +33° 57′ 36″[1]
Number of galaxies 4[1]
Brightest member NGC 7318B[1]
Other designations
HGC 92, Arp 319, VV 288,[1] SQ[2]
See also: Galaxy groups and clusters, List of galaxy clusters
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Stephan's Quintet is a visual grouping of five galaxies of which four form the first compact galaxy group ever discovered.[2] The group was discovered by Édouard Stephan in 1877 at Marseilles Observatory.[3] The group is the most studied of all the compact galaxy groups.[2] 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 out of the five galaxies in the Stephan Quintet 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 to the right 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 postulated beginning of the universe some 10 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[2] and is ~39 million ly[2] from Earth versus the 210-340 million ly of the other five.

NGC 7319 has type 2 Seyfert nucleus.

Contents

[edit] Members

Members of the Hickson Compact Group 92
Name Type[4] R.A. (J2000)[4] Dec. (J2000)[4] Redshift (km/s)[4] Apparent Magnitude[4]
NGC 7317 E4 22h 35m 51.9s +33° 56′ 42″ 6599 ± 26 +14.6
NGC 7318a
(UGC 12099)		 E2 pec 22h 35m 56.7s +33° 57′ 56″ 6630 ± 23 +14.3
NGC 7318b
(UGC 12100)		 SB(s)bc pec 22h 35m 58.4s +33° 57′ 57″ 5774 ± 24 +13.9
NGC 7319 SB(s)bc pec 22h 36m 03.5s +33° 58′ 33″ 6747 ± 7 +14.1
NGC 7320c (R)SAB(s)0/a 22h 36m 20.4s +33° 59′ 06″ 5985 ± 9 +16.7

[edit] Other images

By HST. Credits: NASA/ESA

In infrared by SST

Distances between

[edit] See also


[edit] References

  1. ^ a b c d e NASA/IPAC Extragalactic Database. Results for HCG 92. Retrieved on 2006-09-18.
  2. ^ a b c d e Moles, M.; Marquez, I.; Sulentic, J. W. (1998). "The observational status of Stephan's Quintet". Astronomy and Astrophysics, 334: 473-481. 
  3. ^ Stephan, M. E. (1877). "Nebulæ (new) discovered and observed at the observatory of Marseille, 1876 and 1877, M. Stephan". Monthly Notices of the Royal Astronomical Society 37: 334-339. 
  4. ^ a b c d e NASA/IPAC Extragalactic Database. Results for various galaxies. Retrieved on 2006-10-20.


[edit] External links

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