NGC 2360 (also known as Caroline's Cluster[3] or Caldwell 58) is an open cluster in the constellation Canis Major. It was discovered on 26 February 1783[4] by Caroline Herschel, who described it as a "beautiful cluster of pretty compressed stars near 1/2 degree in diameter".[5] Her notes were overlooked until her brother William included the cluster in his 1786 catalogue of 1000 clusters and nebulae and acknowledged her as the discoverer.[4] The cluster lies 3.5 degrees east of Gamma Canis Majoris and less than one degree northwest of the eclipsing binary star R Canis Majoris; it has a combined apparent magnitude of 7.2.[5] It is 13 arc minutes in diameter.[2] By the western edge of the cluster is the unrelated star, 5.5-magnitude HD 56405.[6]
| NGC 2360 | |
|---|---|
.jpg) | |
| Observation data (J2000 epoch) | |
| Right ascension | 07h 17m 43s[1] |
| Declination | −15° 38′ 29″[1] |
| Apparent magnitude (V) | 7.2[2] |
| Apparent dimensions (V) | 13′[2] |
| Physical characteristics | |
| Other designations | Caroline's Cluster,[3] Caldwell 58, Cr 134, Mel 64[3] |
| Associations | |
| Constellation | Canis Major |
American astronomer Olin J. Eggen surveyed the cluster in 1968, concluding that the brightest star in the field, magnitude-8.96 HD 56847, is likely to lie in the field and not a true member of the cluster. He also identified one or possibly two blue stragglers.[7] These are unexpectedly hot and luminous stars that appear younger than surrounding stars, and have likely developed by sucking matter off companion stars.[8] Four are now recognised to be in the cluster.[9] By analysing the masses of the smallest stars that have evolved into red giants—namely, stars of 1.8 or 1.9 solar masses—Swiss astronomers Jean-Claude Mermilliod and Michel Mayor were able to date the age of the cluster at 2.2 billion years.[10] The cluster has a diameter of around 15 light-years and is located 3700 light-years from Earth.[5]
 Sirius and M41 (lower right), M50 (upper left), and NGC 2360 (lower left) |
Notes edit
- ^ a b "Results for NGC 2360". NGC/IC Project Database. Archived from the original on 2012-05-20. Retrieved 2010-12-03.
- ^ a b c "SEDS Online NGC Database". Results for NGC 2360. Retrieved 2010-12-03.
- ^ a b c "NGC 2360". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2010-12-03.
- ^ a b Hoskin, Michael (2005). "Caroline Herschel as observer" (PDF). Journal for the History of Astronomy. 36 (4): 373–406. Bibcode:2005JHA....36..373H. doi:10.1177/002182860503600402. S2CID 118428465.
- ^ a b c O'Meara, Stephen James (2002). The Caldwell Objects. Cambridge University Press. pp. 231–33. ISBN 978-0-521-82796-6.
- ^ Streicher, Magda (April 2006). "Caroline Herschel's Deepsky Discoveries" (PDF). Deepsky Delights. The Astronomical Society of Southern Africa. pp. 234–36. Retrieved 16 March 2014.
- ^ Eggen, Olin J. (1968). "The Intermediate-Age Cluster NGC 2360" (PDF). The Astrophysical Journal. 152: 83–87. Bibcode:1968ApJ...152...83E. doi:10.1086/149526.
- ^ Fellman, Megan (17 October 2011). "Astronomers Explain 'Blue Stragglers'". News. Evanston, Illinois: Northwestern University. Retrieved 18 March 2014.
- ^ Ahumada, J. A.; Lapasset, E. (2007). "New catalogue of blue stragglers in open clusters". Astronomy and Astrophysics. 463 (2): 789–97. Bibcode:2007A&A...463..789A. doi:10.1051/0004-6361:20054590.
- ^ Mermilliod, Jean-Claude; Mayor, Michel (1990). "Red Giants in Open Clusters. III – Binarity and Stellar Evolution in Five Intermediate-age Clusters: NGC 2360, 2423, 5822, 6811, and IC 4756" (PDF). Astronomy and Astrophysics. 273 (1): 61–72. Bibcode:1990A&A...237...61M.
External links edit
- NGC 2360 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images