Messier 13

This article is about the globular cluster M13. For the galaxy cluster in Hercules, see Abell 2151.

Messier 13
The heart of Hercules Globular Cluster; Credit: ESA/Hubble and NASA
Observation data (J2000 epoch)
Class	V
Constellation	Hercules
Right ascension	16h 41m 41.44s
Declination	+36° 27′ 36.9″
Distance	25,100 light years
Apparent magnitude (V)	+5.8
Apparent dimensions (V)	20 arcmins
Physical characteristics
Mass	6×105  M☉ (1036 kg)
Radius	84 ly
Estimated age	1.4×1010 yr
Notable features	one of the best-known clusters of the northern hemisphere
Other designations	NGC 6205
See also: Globular cluster, List of globular clusters

Messier 13 or 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

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

It is located at right ascension 16^h 41.7^m 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.

Characteristics

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, designed to communicate the existence of human life to hypothetical extraterrestrials, was transmitted toward M13. The reason was that with a higher star density, the chances of a life harboring planet with intelligent life forms, were believed to be higher. Even though the message was transmitted, M13 will no longer be in that location when it arrives. The sending of the message was more of a technological demonstration, rather than an actual attempt to contact life.

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

M13 is in "armpit" of Hercules constellation

See also

• New General Catalogue
• Messier object
• List of globular clusters

External links

• 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)
• Messier 13 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images