NGC 3201

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NGC 3201
NGC 3201 Hubble WikiSky.jpg
NGC 3201 by Hubble Space Telescope; 3.5′ view
Credit: NASA/STScI/WikiSky
Observation data (J2000 epoch)
Class X[1]
Constellation Vela
Right ascension 10h 17m 36.82s[2]
Declination –46° 24′ 44.9″[2]
Distance 16.3 kly (5.0 kpc)[3]
Apparent magnitude (V) +8.24[4]
Apparent dimensions (V) 18′.2
Physical characteristics
Mass 2.54×105[5] M
Radius 40 ly[6]
VHB 14.77
Metallicity  = –1.24[7] dex
Estimated age 10.24 Gyr[7]
Other designations GCl 15,[4] GC 2068, h 3238, Dun 445, Bennett 44, Caldwell 79[8]
See also: Globular cluster, List of globular clusters
Colour-composite image of NGC 3201, obtained with the WFI instrument on the ESO/MPG 2.2-m telescope at La Silla Observatory

NGC 3201 (also known as Caldwell 79) is a low galactic latitude globular cluster in the southern constellation of Vela. It has a very low central concentration of stars.[9] This cluster was discovered by James Dunlop on May 28, 1826 and listed it in his 1827 catalogue. He described it as "a pretty large pretty bright round nebula, 4′ or 5′ diameter, very gradually condensed towards the centre, easily resolved into stars; the figure is rather irregular, and the stars are considerably scattered on the south".[10]

The radial velocity of this cluster is unusually high at 490 km/s, larger than any other cluster known. This corresponds to a peculiar velocity of 240 km/s. While high, this is lower than the escape velocity of the Milky Way galaxy.[10] It is located at a distance of 16,300 light years from the Sun and has an estimated 254,000 times the mass of the Sun.[3] This cluster is about 10.24 billion years old.[7]

The stellar population of this cluster is inhomogeneous, varying with distance from the core. The effective temperature of the stars shows an increase with greater distance, with the redder and cooler stars tending to be located closer to the core. As of 2010, is one of only two clusters (including Messier 4) that shows a definite inhomogeneous population.[11]


  1. ^ Shapley, Harlow; Sawyer, Helen B. (August 1927), "A Classification of Globular Clusters", Harvard College Observatory Bulletin (849): 11–14, Bibcode:1927BHarO.849...11S. 
  2. ^ a b Goldsbury, Ryan; et al. (December 2010), "The ACS Survey of Galactic Globular Clusters. X. New Determinations of Centers for 65 Clusters", The Astronomical Journal, 140 (6): 1830–1837, Bibcode:2010AJ....140.1830G, arXiv:1008.2755Freely accessible, doi:10.1088/0004-6256/140/6/1830. 
  3. ^ a b Paust, Nathaniel E. Q.; et al. (February 2010), "The ACS Survey of Galactic Globular Clusters. VIII. Effects of Environment on Globular Cluster Global Mass Functions", The Astronomical Journal, 139 (2): 476–491, Bibcode:2010AJ....139..476P, doi:10.1088/0004-6256/139/2/476. 
  4. ^ a b "SIMBAD Astronomical Object Database", Results for NGC 3201, retrieved 2006-11-16. 
  5. ^ Boyles, J.; et al. (November 2011), "Young Radio Pulsars in Galactic Globular Clusters", The Astrophysical Journal, 742 (1): 51, Bibcode:2011ApJ...742...51B, arXiv:1108.4402Freely accessible, doi:10.1088/0004-637X/742/1/51. 
  6. ^ distance × sin( diameter_angle / 2 ) = 40 ly. radius
  7. ^ a b c Forbes, Duncan A.; Bridges, Terry (May 2010), "Accreted versus in situ Milky Way globular clusters", Monthly Notices of the Royal Astronomical Society, 404 (3): 1203–1214, Bibcode:2010MNRAS.404.1203F, arXiv:1001.4289Freely accessible, doi:10.1111/j.1365-2966.2010.16373.x. 
  8. ^ "NGC 3201", Deep Sky Observer's Companion, retrieved 2012-04-28. 
  9. ^ Webb, N. A.; Wheatley, P. J.; Barret, D. (2005), XMM-Newton X-ray and optical observations of the globular clusters M 55 and NGC 3201, Bibcode:2005yCat..34450155W, arXiv:astro-ph/0509085Freely accessible, doi:10.1051/0004-6361:20053010. 
  10. ^ a b O'Meara, Stephen James (2002), The Caldwell Objects, Deep-Sky Companions, Cambridge University Press, pp. 314–315, ISBN 0521827965. 
  11. ^ Kravtsov, V.; et al. (March 2010), "Evidence of the inhomogeneity of the stellar population in the differentially reddened globular cluster NGC 3201", Astronomy and Astrophysics, 512: L6, Bibcode:2010A&A...512L...6K, arXiv:1004.5583Freely accessible, doi:10.1051/0004-6361/200913749. 

External links[edit]

Coordinates: Sky map 10h 17m 36.76s, −46° 24′ 40.4″