NGC 6281

NGC 6281
Observation data (J2000 epoch)
Constellation	Scorpius
Right ascension	17h 04.7m[1]
Declination	−37° 59′[1]
Distance	1,611 ly (494 pc)[1]
Apparent magnitude (V)	5.4[2]
Physical characteristics
Mass	214[3] M☉
Estimated age	3.23 × 108 yr[1]
Other designations	C 1701-378[2]
See also: Open cluster, List of open clusters

NGC 6281 is an open cluster of stars in the constellation Scorpius. It was not included in the Messier or Caldwell catalogues of nebulous objects, but it is the brightest such cluster in the constellation to be left out of both. It is readily observed with binoculars or a small telescope; it is located about 2° to the east of Mu Scorpii. James Dunlop described the cluster as a "curiously curved line of pretty bright stars, with many stars mixt". John Herschel then described the cluster as both "pretty bright" and "pretty rich".^[4][5]

This cluster has a tidal radius of 26 ly (8.0 pc) and a mass of about 214 solar masses.^[3] It is classified as a type II2p cluster and has 55 members with a visual magnitude of 13.5 or greater within 20 arcminutes of the center.^[6] The brightest member is 9th magnitude. Overall, the cluster has an integrated visual magnitude of 5.4.^[5]

References

1. ^ ^{a b c d} Kharchenko, N. V.; Piskunov, A. E.; Röser, S.; Schilbach, E.; Scholz, R.-D. (August 2005). "Astrophysical parameters of Galactic open clusters". Astronomy and Astrophysics 438 (3): 1163–1173. arXiv:astro-ph/0501674. Bibcode 2005A&A...438.1163K. doi:10.1051/0004-6361:20042523. 
2. ^ ^{a b} "NGC 6281 -- Cluster of Stars". SIMBAD. Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-id?Ident=NGC+6281. Retrieved 2011-02-09. 
3. ^ ^{a b} Piskunov, A. E.; Schilbach, E.; Kharchenko, N. V.; Röser, S.; Scholz, R.-D. (January 2008). "Tidal radii and masses of open clusters". Astronomy and Astrophysics 477 (1): 165–172. Bibcode 2008A&A...477..165P. doi:10.1051/0004-6361:20078525. 
4. ^ Crossen, Craig; Rhemann, Gerald (2004). Sky vistas: astronomy for binoculars and richest-field telescopes. Springer. p. 52. ISBN 3211008519. 
5. ^ ^{a b} O'Meara, Stephen James (2007). Hidden treasures: Deep-sky companions. Cambridge University Press. p. 400. ISBN 0521837049. 
6. ^ Schneider, H.. "Stromgren photometry of open clusters. I - NGC 6281, NGC 6405". Astronomy and Astrophysics Supplement Series 61: 45–51. Bibcode 1985A&AS...61...45S.