The heart of Hercules Globular Cluster;
Credit: ESA/Hubble and NASA
|Observation data (J2000 epoch)|
|Right ascension||16h 41m 41.24s|
|Declination||+36° 27′ 35.5″|
|Distance||22.2 kly (6.8 kpc)|
|Apparent magnitude (V)||+5.8|
|Apparent dimensions (V)||20 arcmins|
|Estimated age||11.65 Gyr|
|Notable features||one of the best-known clusters of the northern hemisphere|
|Other designations||NGC 6205|
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
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.
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
The Arecibo message of 1974, containing encoded information about human race, DNA, atomic numbers, Earth position, was beamed there for being picked up by a potential extraterrestrial civilization. It will reach the cluster in 25,000 years.
 Literary references
- The science fiction novellas "Sucker Bait" by Isaac Asimov and "Question and Answer" by Poul Anderson take place on Troas, a world within M13.
- In the science fiction series Perry Rhodan, M13 is the location of Arkon, the home world of the race of Arkonides.
- In author Dan Simmon's Hyperion Cantos the Hercules cluster is where Earth was secretly moved to after it was supposedly destroyed.
- In The Sirens of Titan, Kurt Vonnegut writes "Every passing hour brings the Solar System forty-three thousand miles closer to Globular Cluster M13 in Hercules – and still there are some misfits who insist that there is no such thing as progress."
- Deliberately engineering a star in Messier 13 to go nova was part of the Cybermen’s complicated plot in the 1968 Doctor Who story The Wheel in Space.
- In Bill Amend's popular comic strip FoxTrot, Jason Fox mentions observing the M13 Globular Cluster
 See also
- Shapley, Harlow; Sawyer, Helen B. (August 1927), "A Classification of Globular Clusters", Harvard College Observatory Bulletin 849 (849): 11–14, Bibcode:1927BHarO.849...11S.
- 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.
- 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.
- "SIMBAD Astronomical Object Database". Results for NGC 6205. Retrieved 2006-11-15.
- 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.
- distance × sin( diameter_angle / 2 ) = 84 ly radius
- 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.
|Wikimedia Commons has media related to: Messier 13|
- Messier 13, SEDS Messier pages
- Messier 13, Galactic Globular Clusters Database page
- Messier 13, High-resolution LRGB image based on 2 hrs total exposure
- M13 Hercules Globular photo detail Dark Atmospheres
- Messier 13, Image by Waid Observatory
- NightSkyInfo.com – M13, the Hercules Globular Cluster
- Photometric study of the V2 cepheid in M13
- Period, Amplitude and Light Curve of V38 in M13
- Great Globular Cluster in Hercules (Messier 13/NGC 6205)
- Rothery, David; Bauer, Amanda; Dhillon, Vik; Lawrence, Pete; Chapman, Allan; Fohring, Dora. "M13 – Hercules Globular Cluster". Deep Sky Video. Brady Haran.
- Messier 13 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images