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Messier 69

Coordinates: Sky map 18h 31m 23.23s, −32° 20′ 52.7″
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Messier 69
M69 by Hubble Space Telescope; 3.5′ view
Credit: NASA/STScI/WikiSky
Observation data (J2000 epoch)
ClassV[1]
ConstellationSagittarius
Right ascension18h 31m 23.10s[2]
Declination−32° 20′ 53.1″[2]
Distance29.7 kly (9.1 kpc)
Apparent magnitude (V)+8.31[3]
Apparent dimensions (V)9′.8
Physical characteristics
Radius42 ly[4]
Metallicity = –0.78[5] dex
Estimated age13.06 Gyr[5]
Other designationsM69, NGC 6637, GCl 96[3]
See also: Globular cluster, List of globular clusters

Messier 69 (also known as M69 or NGC 6637) is a globular cluster in the constellation Sagittarius. It was discovered by Charles Messier on August 31, 1780, the same night he discovered M70. At the time, he was searching for an object described by Nicolas-Louis de Lacaille in 1751–2 and thought he had rediscovered it, but it is unclear if Nicolas-Louis de Lacaille actually described M69.

M69 is at a distance of about 29,700 light-years away from Earth and has a spatial radius of 42 light-years. It is a close neighbor of globular cluster M70, with 1,800 light-years separating the two objects; both of these clusters lie close to the galactic center. It is one of the most metal-rich globular clusters known.[citation needed]

  • As globular clusters go, M69 is one of the most metal-rich on record.[6]
    As globular clusters go, M69 is one of the most metal-rich on record.[6]
  • Map showing location of M69 (Roberto Mura)
    Map showing location of M69 (Roberto Mura)

References

  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, arXiv:1008.2755, Bibcode:2010AJ....140.1830G, doi:10.1088/0004-6256/140/6/1830.
  3. ^ a b "NGC 6637". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved November 17, 2006.
  4. ^ distance × sin( diameter_angle / 2 ) = 42 ly. radius
  5. ^ a b 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.
  6. ^ "Cosmic riches". ESA/Hubble Picture of the Week. Retrieved October 3, 2012.
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