Messier 55

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Messier 55
Observation data (J2000 epoch)
Class XI
Constellation Sagittarius
Right ascension 19h 39m 59.40s[1]
Declination -30° 57′ 43.5″[1]
Distance 17.3 kly[citation needed] (5.3 kpc)
Apparent magnitude (V) +7.42[1]
Apparent dimensions (V) 19′.0
Physical characteristics
Mass kg ( M{\odot})
Radius 48 ly[2]
Other designations M55, NGC 6809, GCl 113[1]
See also: Globular cluster, List of globular clusters
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Messier 55 (also known as M55 or NGC 6809) is a globular cluster in the constellation Sagittarius. It was discovered by Nicolas Louis de Lacaille in 1751 and catalogued by Charles Messier in 1778. M55 is at a distance of about 17,300 light-years away from Earth. Only about half a dozen variable stars have been discovered in M55.

[edit] External links

[edit] References

  1. ^ a b c d SIMBAD Astronomical Database. Results for NGC 6809. Retrieved on 2006-11-16.
  2. ^ distance × sin( diameter_angle / 2 ) = 48 ly. radius


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