NGC 4833

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NGC 4833
A sky full of stars NGC 4833.jpg
NGC 4833 is one of the over 150 globular clusters known to reside within the Milky Way. [1]
Observation data (J2000 epoch)
Class VIII [2]
Constellation Musca
Right ascension 12h 59m 33.92s [3]
Declination –70° 52′ 35.4″ [3]
Distance 21.5  kly (6.6  kpc) [4]
Apparent magnitude (V)+7.79 [5]
Apparent dimensions (V)13.5′ [6]
Physical characteristics
Absolute magnitude −8.16 [7]
Mass4.10×105 [4]   M☉
Radius42 ly [8]
Metallicity  = –2.02 [7] dex
Estimated age12.54  Gyr [9]
Other designations NGC  4833, Caldwell  105, GCl 21, [5] Lacaille I.4, Dunlop 164, Bennett 56
See also: Globular cluster, List of globular clusters
The location of NGC 4833 (labelled in red) NGC4833Location.png
The location of NGC 4833 (labelled in red)

NGC 4833 is a globular cluster discovered by Abbe Lacaille during his 1751-1752 journey to South Africa, and catalogued in 1755. [10] It was subsequently observed and catalogued by James Dunlop and Sir John Herschel whose instruments could resolve it into individual stars. [6]

Contents

The globular cluster is situated in the very southerly constellation Musca [6] at a distance of 21,500 light years from Earth. [4] It is located near the Coalsack Nebula and is partially obscured by this dusty region of the galactic plane. [7] After corrections for the reddening by dust, evidence was obtained that it is in the order of 2 billion years older than globular clusters M5 or M92. [11]

This is a massive, metal-poor globular cluster that shows evidence for multiple generations of stars. [12] It is an old halo cluster of the Oosterhoff type II. The orbit of the cluster through the galaxy is very eccentric, with an eccentricity of 0.84 that carries it close to the galactic center. The cluster has likely lost a significant portion of its original mass due to interactions with the galactic bulge. [7]

A 2012 survey for variable stars identified six SX Phe, two eclipsing binaries (including a W UMa), and 19 RR Lyr variables. [13] [14]

See also

References

  1. ↑ "A sky full of stars", www.spacetelescope.org, retrieved 1 August 2016.
  2. ↑ Shapley, Harlow; Sawyer, Helen B. (August 1927), "A Classification of Globular Clusters", Harvard College Observatory Bulletin, 849 (849): 11–14, Bibcode:1927BHarO.849...11S.
  3. 1 2 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, arXiv: 1008.2755 , Bibcode:2010AJ....140.1830G, doi:10.1088/0004-6256/140/6/1830, S2CID   119183070.
  4. 1 2 3 Boyles, J.; et al. (November 2011), "Young Radio Pulsars in Galactic Globular Clusters", The Astrophysical Journal, 742 (1): 51, arXiv: 1108.4402 , Bibcode:2011ApJ...742...51B, doi:10.1088/0004-637X/742/1/51, S2CID   118649860.
  5. 1 2 "NGC 4833". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2006-11-17.
  6. 1 2 3 O'Meara, Stephen James (2016), Deep-Sky Companions: The Caldwell Objects, Cambridge University Press, pp. 480–482, ISBN   9781316033531.
  7. 1 2 3 4 Carretta, E.; et al. (April 2014), "The extreme chemistry of multiple stellar populations in the metal-poor globular cluster NGC 4833", Astronomy & Astrophysics, 564, id. A60, arXiv: 1401.7325 , Bibcode:2014A&A...564A..60C, doi:10.1051/0004-6361/201323321.
  8. ↑ distance × tan( diameter_angle / 2 ) = 42 ly. radius
  9. ↑ 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, arXiv: 1001.4289 , Bibcode:2010MNRAS.404.1203F, doi: 10.1111/j.1365-2966.2010.16373.x , S2CID   51825384.
  10. ↑ Jones, K. G. (March 1969), "The search for the nebulae - VI", Journal of the British Astronomical Association, 79: 213–222, Bibcode:1969JBAA...79..213J.
  11. ↑ Melbourne, Jason; et al. (December 2000), "CCD Photometry of the Globular Cluster NGC 4833 and Extinction Near the Galactic Plane", The Astronomical Journal, 120 (6): 3127–3138, arXiv: astro-ph/0009401 , Bibcode:2000AJ....120.3127M, doi:10.1086/316869.
  12. ↑ Carretta, Eugenio (May 2021), "Potassium abundances in multiple stellar populations of the globular cluster NGC 4833", Astronomy & Astrophysics, 649, id. A154, arXiv: 2103.10441 , Bibcode:2021A&A...649A.154C, doi:10.1051/0004-6361/202140684.
  13. ↑ Darragh, A. N.; Murphy, B. W. (July 2012), "New SX Phoenicis Variables in the Globular Cluster NGC 4833", Journal of the Southeastern Association for Research in Astronomy, 6: 72–77, arXiv: 1205.1025 , Bibcode:2012JSARA...6...72D.
  14. ↑ Demers, S.; Wehlau, A. (August 1977), "Variable stars of NGC 4833", Astronomical Journal, 82: 620–625, Bibcode:1977AJ.....82..620D, doi:10.1086/112095.

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