NGC 2244

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NGC 2244
Rosette Nebula in Monoceros.jpg
Observation data (J2000 epoch)
Right ascension6h 31m 54s[1]
Declination+4° 56′[1]
Distance5.2 kly
Apparent magnitude (V)4.8[1]
Apparent dimensions (V)24′
Physical characteristics
Radius18 ly[2]
Other designationsCaldwell 50, Satellite Cluster,[3] NGC 2239,[4] Cr 99
See also: Open cluster, List of open clusters
An infrared Spitzer Space Telescope (SIRT) image of NGC 2244.

NGC 2244 (also known as Caldwell 50 or the Satellite Cluster) is an open cluster in the Rosette Nebula, which is located in the constellation Monoceros. This cluster has several O-type stars, super hot stars that generate large amounts of radiation and stellar wind.

The age of this cluster has been estimated to be less than 5 million years. The brightest star in the cluster is 12 Monocerotis, a foreground K-class giant. The two brightest members of the cluster are HD 46223 of spectral class O4V, 400,000 times brighter than the Sun, and approximately 50 times more massive, and HD 46150, whose spectral type is O5V, has a luminosity 450,000 time larger than that of our star, and is up to 60 times more massive, but it may actually be a double star.[5]


  1. ^ a b c "NGC 2244". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2007-04-20.
  2. ^ distance × sin( angular diameter / 2 )
  3. ^ "The Rosette Nebula In Hubble Palette". Sky & Telescope. Retrieved 2020-06-23.
  4. ^ "Notes on the NGC objects, particularly those missing, misidentified, or otherwise unusual (ngcnotes.all)". Historically-aware NGC/IC Positions and Notes. Retrieved 2019-08-11.
  5. ^ A quantitative study of O stars in NGC 2244 and the Monoceros OB2 association, Martins, F.; Mahy, L.; Hillier, D. J.; Rauw, G., Astronomy and Astrophysics 538, pp. A39, Bibcode:2012A&A...538A..39M, doi:10.1051/0004-6361/201117458.

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