NGC 6087

NGC 6087 (also known as Caldwell 89 or the S Normae Cluster) is an open cluster of 40 or more[2][3] stars centered on the Cepheid variable S Normae in the constellation Norma. At a distance of about 3500 ly and covering a field of almost one quarter of a degree, the stars range from seventh- to eleventh-magnitude, the brightest being 6.5 magnitude S Normae. The aggregate visual magnitude of the cluster is about 5.4.

NGC 6087
Observation data (J2000 epoch)
ConstellationNorma
Right ascension 16h 18m 48s[1]
Declination−57° 56′[1]
Distance~3500LY (~1000pc)
Apparent magnitude (V)5.4
Apparent dimensions (V)12′
Physical characteristics
Other designationsS Normae Cluster, Caldwell 89, Cr 300
Map showing the location of NGC 6087

Spectral analysis of the radial motion of the stars confirm that S Normae is a member of the cluster,[3] and the period/luminosity relationship of Cepheid variables allows the distance to be determined with confidence.

References
  1. "NGC 6087". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2007-04-18.
  2. Burnham's Celestial Handbook gives the number 40, though other studies go as high as 349; see Stephen James O'Meara, The Caldwell Objects, Cambridge University Press, 2002, p. 351.
  3. A. U. Landolt (1964). "The Galactic Cluster NGC 6087". Astrophysical Journal Supplement. 8: 329–351. Bibcode:1964ApJS....8..329L. doi:10.1086/190092. Retrieved 4 April 2013.


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