Astronomy:NGC 4833

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NGC 4833
File:300px
NGC 4833 is one of the over 150 globular clusters known to reside within the Milky Way.[1]
Observation data (J2000 epoch)
ClassVIII[2]
ConstellationMusca
Right ascension 12h 59m 33.92s[3]
Declination–70° 52′ 35.4″[3]
Distance21.5 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[Fe/H] = –2.02[7] dex
Estimated age12.54 Gyr[9]
Other designationsNGC 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)

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]

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, http://www.spacetelescope.org/images/potw1631a/, retrieved 1 August 2016. 
  2. ↑ "A Classification of Globular Clusters", Harvard College Observatory Bulletin 849 (849): 11–14, August 1927, Bibcode: 1927BHarO.849...11S. 
  3. ↑ 3.0 3.1 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, doi:10.1088/0004-6256/140/6/1830, Bibcode: 2010AJ....140.1830G. 
  4. ↑ 4.0 4.1 4.2 Boyles, J. et al. (November 2011), "Young Radio Pulsars in Galactic Globular Clusters", The Astrophysical Journal 742 (1): 51, doi:10.1088/0004-637X/742/1/51, Bibcode: 2011ApJ...742...51B. 
  5. ↑ 5.0 5.1 "NGC 4833". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=NGC+4833. 
  6. ↑ 6.0 6.1 6.2 O'Meara, Stephen James (2016), Deep-Sky Companions: The Caldwell Objects, Cambridge University Press, pp. 480–482, ISBN 9781316033531, https://books.google.com/books?id=evkODQAAQBAJ&pg=PA480. 
  7. ↑ 7.0 7.1 7.2 7.3 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, doi:10.1051/0004-6361/201323321, Bibcode: 2014A&A...564A..60C. 
  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, doi:10.1111/j.1365-2966.2010.16373.x, Bibcode: 2010MNRAS.404.1203F. 
  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, doi:10.1086/316869, Bibcode: 2000AJ....120.3127M. 
  12. ↑ Carretta, Eugenio (May 2021), "Potassium abundances in multiple stellar populations of the globular cluster NGC 4833", Astronomy & Astrophysics 649: id. A154, doi:10.1051/0004-6361/202140684, Bibcode: 2021A&A...649A.154C. 
  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, Bibcode: 2012JSARA...6...72D. 
  14. ↑ Demers, S.; Wehlau, A. (August 1977), "Variable stars of NGC 4833", Astronomical Journal 82: 620–625, doi:10.1086/112095, Bibcode: 1977AJ.....82..620D. 

Further reading

  • Roederer, Ian U.; Thompson, Ian B. (June 2015), "Detailed abundances of 15 stars in the metal-poor globular cluster NGC 4833", Monthly Notices of the Royal Astronomical Society 449 (4): 3889–3910, doi:10.1093/mnras/stv546, Bibcode: 2015MNRAS.449.3889R. 
  • Kopacki, Grzegorz (February 2014), "Wide-field variability survey of the globular cluster NGC 4833", Precision Asteroseismology, Proceedings of the International Astronomical Union, IAU Symposium, 301, pp. 441–442, doi:10.1017/S1743921313014956, Bibcode: 2014IAUS..301..441K. 
  • Samus, N. et al. (March 1995), "A new photographic C-M diagram for NGC 4833.", Astronomy and Astrophysics Supplement 109: 479–486, Bibcode: 1995A&AS..109..479S. 
  • McLaughlin, Dean B., ed. (1946), "Eleven variable stars in the globular cluster NGC 4833", Publications of the American Astronomical Society (Published by the AAS) 10: 264, Bibcode: 1946PAAS...10..264W. 

Coordinates: Sky map 12h 59m 34.98s, −70° 52′ 28.6″



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