Messier Index/M55

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Messier 55
M55.jpg
Observation data (w: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]

Messier 55 (also known as M55 or NGC 6809) is a w:globular cluster in the w:constellation Sagittarius. It was discovered by w:Nicolas Louis de Lacaille in w:1751 and catalogued by w:Charles Messier in w:1778. M55 is at a distance of about 17,300 w:light-years away from w:Earth. Only about half a dozen w:variable stars have been discovered in M55.

External links

References

  1. a b c d "SIMBAD Astronomical Database". Results for NGC 6809. http://simbad.u-strasbg.fr/Simbad. Retrieved 2006-11-16. 
  2. distance × sin( diameter_angle / 2 ) = 48 ly. radius