NGC 6231 (also known as Caldwell 76) is an open cluster in the southern sky located half a degrees north of Zeta Scorpii. NGC 6231 is part of a swath of young, bluish stars in the constellation Scorpius known as the Scorpius OB1 association. The star Zeta1 (HR 6262) is a member of this association, while its brighter apparent partner, Zeta2 (HR 6271), is only 150 ly from Earth and so is not a member.
|Observation data (J2000.0 epoch)|
|Right ascension||16h 54m|
|Distance||5,600±400 ly (1,700±130 parsec)|
|Apparent magnitude (V)||2.6|
|Apparent dimensions (V)||15.0′|
|Estimated age||2–7 million years|
|Other designations||NGC 6171, Caldwell 76, Collinder 315, De Cheseaux 9, Dunlop 499, Ha. I.7, Lacaille II.13, Melotte 153|
This cluster is estimated about 2–7 million years old, and is approaching the Solar System at 22 km/s. The cluster and association lie in the neighboring Sagittarius Arm of the Milky Way. Zeta1 Scorpii (spectral type O8 and magnitude 4.71.) is the brightest star in the association, and one of the most radiant stars known in the galaxy.
The cluster was discovered by Giovanni Batista Hodierna before 1654. Hodierna listed it as Luminosae in his catalogue of deep sky observations. This catalogue was included in his book De Admirandis Coeli Characteribuse published in 1654 at Palermo. It was independently observed by other astronomers after Hodierna, including Edmond Halley (1678), Jean-Philippe de Cheseaux (1745-46), and Abbe Lacaille (1751-52).
The cluster forms the head of the False Comet, a wider collection of stars from Scorpius OB1 running northward from Zeta Scorpii and NGC 6231 roughly halfway toward Mu Scorpii. The tail is formed by two clusters, Collinder 316 and Trumpler 24. Trumpler 24 is surrounded by the emission nebula IC 4628, also known as the Prawn Nebula, where the tail appears to fan out.
- Kuhn, Michael A.; Hillenbrand, Lynne A.; Sills, Alison; Feigelson, Eric D.; Getman, Konstantin V. (2018). "Kinematics in Young Star Clusters and Associations with Gaia DR2". The Astrophysical Journal. 870 (1): 32. arXiv:1807.02115. Bibcode:2019ApJ...870...32K. doi:10.3847/1538-4357/aaef8c.
- Reipurth, B. (2008). "Young Stars in NGC 6231 and the Sco OB1 Association". In Reipurth, B. (ed.). Handbook of Star Forming Regions, Volume II: The Southern Sky ASP Monograph Publications. 5. p. 401. Bibcode:2008hsf2.book..401R. ISBN 978-1-58381-670-7.
- Kuhn, M. A.; Medina, N.; Getman, K. V.; et al. (2017). "The Structure of the Young Star Cluster NGC 6231. I. Stellar Population". The Astronomical Journal. 154 (3): 87. arXiv:1706.00017. Bibcode:2017AJ....154...87K. doi:10.3847/1538-3881/aa76e8.
- Sky Catalogue 2000.0
- Crossen & Tirion, Binocular Astronomy, p. 119.
- Shylaja, B. S (1988). "Study of the Wolf-Rayet members of the cluster NGC 6231". Journal of Astrophysics and Astronomy. 9 (3): 161–172. Bibcode:1988JApA....9..161S. doi:10.1007/BF02715061.
- The distinction between OIafpe and WNLha stars. A spectral analysis of HD 151804, HD 152408 and HDE 313846.
- Stars visible to the naked eye. It meanings "luminous" in Latin.
- Michael E. Bakich (July 17, 2014). "The Northern Jewel Box, globular cluster M12, and the Bug Nebula". astronomy.com. Retrieved August 5, 2019.
|Wikimedia Commons has media related to NGC 6231.|
- NGC 6231 at DOCdb (Deep Sky Observer's Companion)
- NGC 6231 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images