Messier 13

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Messier 13
Heart of M13 Hercules Globular Cluster.jpg
The heart of Hercules Globular Cluster;
Credit: ESA/Hubble and NASA
Observation data (J2000 epoch)
Class V[1]
Constellation Hercules
Right ascension 16h 41m 41.24s[2]
Declination +36° 27′ 35.5″[2]
Distance 22.2 kly (6.8 kpc)[3]
Apparent magnitude (V) +5.8[4]
Apparent dimensions (V) 20 arcmins
Physical characteristics
Mass 6×105[5] M
Radius 84 ly[6]
Metallicity –1.33[7] dex
Estimated age 11.65 Gyr[7]
Notable features one of the best-known clusters of the northern hemisphere
Other designations NGC 6205[4]
See also: Globular cluster, List of globular clusters

Messier 13 (M13), also designated NGC 6205 and sometimes called the Great Globular Cluster in Hercules or the Hercules Globular Cluster, is a globular cluster of about 300,000 stars in the constellation of Hercules.

Discovery and visibility[edit]

M13 was discovered by Edmond Halley in 1714, and catalogued by Charles Messier on June 1, 1764.

It is located at right ascension 16h 41.7m and declination +36° 28'. With an apparent magnitude of 5.8, it is barely visible with the naked eye on a very clear night. Its diameter is about 23 arc minutes and it is readily viewable in small telescopes. Nearby is NGC 6207, a 12th magnitude edge-on galaxy that lies 28 arc minutes directly north east. A small galaxy, IC 4617, lies halfway between NGC 6207 and M13, north-northeast of the large globular cluster's center.

Wide field image of Messier 13.

Characteristics[edit]

M13 is about 145 light-years in diameter, and it is composed of several hundred thousand stars, the brightest of which is the variable star V11 with an apparent magnitude of 11.95. M13 is 25,100 light-years away from Earth.

Arecibo message[edit]

The Arecibo message of 1974, containing encoded information about the human race, DNA, atomic numbers, Earth's position, and other information, was beamed towards M13 to allow it to be picked up by potential extraterrestrial civilizations in the cluster. The message will reach the cluster in 25,000 years.

Literary references[edit]

M13 is in "armpit" of Hercules constellation

See also[edit]

References[edit]

  1. ^ Shapley, Harlow; Sawyer, Helen B. (August 1927), "A Classification of Globular Clusters", Harvard College Observatory Bulletin 849 (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. ^ 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 6205. Retrieved 2006-11-15. 
  5. ^ Leonard, Peter J. T.; Richer, Harvey B.; Fahlman, Gregory G. (1992), "The mass and stellar content of the globular cluster M13", Astronomical Journal 104: 2104, Bibcode:1992AJ....104.2104L, doi:10.1086/116386. 
  6. ^ distance × sin( diameter_angle / 2 ) = 84 ly radius
  7. ^ 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. 

External links[edit]

Coordinates: Sky map 16h 41m 41.44s, +36° 27′ 36.9″