NGC 2204

NGC 2204 is an open cluster of stars in the Canis Major constellation. It was discovered by the German-English astronomer William Herschel on 6 February 1785.^[5] The cluster has an integrated visual magnitude of 8.6 and spans a diameter of 10.0′. Resolving the individual member stars is a challenge with a 10 to 12-inch amateur telescope.^[3] It is located at a distance of approximately 13,400 light years from the Sun.^[2] The cluster shows a mean radial velocity of +91.38±0.30 km/s relative to the Sun,^[6] and is orbiting the inner galactic disk region about 1 kpc below the galactic plane.^[2]

NGC 2204
NGC 2204, Digitized Sky Survey
Observation data (J2000.0 epoch)
Right ascension	06h 15m 31.7s[1]
Declination	−18° 40′ 12″[1]
Distance	13.4 ± 1.3 kly (4.1 ± 0.4 kpc)[2]
Apparent magnitude (V)	8.6[3]
Apparent dimensions (V)	10.0′[3]
Physical characteristics
Radius	16.25ly
Estimated age	2.0±0.3 Gyr[2]
Other designations	Collinder 88, Melotte 44[4]
Associations
Constellation	Canis Major
See also: Open cluster, List of open clusters

This is a rich but diffuse cluster with a Trumpler class of III 3m,^[7][8] spanning a physical diameter of about 55 ly (17 pc).^[9] It is an older cluster with an estimated age of 2.0±0.3 billion years.^[10] The metallicity is correspondingly poor,^[11][8] showing an abundance of iron about 59% of that in the Sun.^[2] There is a prominent giant branch clump on the HR diagram.^[7] The cluster has a significant population of blue stragglers,^[12][11] an indicator of past stellar mergers. It has a pair of candidate chemically peculiar stars,^[8] and five variable stars have been discovered, including four eclipsing variables.^[9]

References

1. Tarricq, Y.; et al. (March 2021). "3D kinematics and age distribution of the open cluster population". Astronomy & Astrophysics. 647. id. A19. arXiv:2012.04017. Bibcode:2021A&A...647A..19T. doi:10.1051/0004-6361/202039388.
2. Jacobson, Heather R.; et al. (February 2011). "A Chemical Abundance Study of Red Giants in Open Clusters NGC 2204 and NGC 2243". The Astronomical Journal. 141 (2): 16. Bibcode:2011AJ....141...58J. doi:10.1088/0004-6256/141/2/58. S2CID 120444023. 58.
3. O'Meara, Stephen James (2007). Herschel 400 Observing Guide. Cambridge University Press. p. 48. ISBN 9780521858939.
4. "NGC 2204". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 9 March 2024.
5. Frommert, Hartmut; Kronberg, Christine. "NGC 2204". SEDS. Retrieved 9 July 2015.
6. Mermilliod, J. -C.; Mayor, M. (August 2007). "Red giants in open clusters. XII. Six old open clusters NGC 2112, 2204, 2243, 2420, 2506, 2682". Astronomy and Astrophysics. 470 (3): 919–926. Bibcode:2007A&A...470..919M. doi:10.1051/0004-6361:20077198.
7. Hawarden, T. G. (January 1976). "NGC 2204: an old open cluster in the halo". Monthly Notices of the Royal Astronomical Society. 174: 225–239. Bibcode:1976MNRAS.174..225H. doi:10.1093/mnras/174.1.225.
8. Dawson, D. W. (February 1981). "The open cluster NGC 2204". Astronomical Journal. 86: 237–241. Bibcode:1981AJ.....86..237D. doi:10.1086/112879.
9. Rozyczka, M.; et al. (December 2007). "Variable Stars in the Field of the Open Cluster NGC2204". Acta Astronomica. 57: 323–329. arXiv:0803.1045. Bibcode:2007AcA....57..323R.
10. Salaris, M.; et al. (January 2004). "The age of the oldest Open Clusters". Astronomy and Astrophysics. 414 (2): 163–174. arXiv:astro-ph/0310363. Bibcode:2011AJ....141...58J. doi:10.1051/0004-6361:20031578.
11. Siegel, Michael H.; et al. (July 2019). "The Swift UVOT Stars Survey. III. Photometry and Color-Magnitude Diagrams of 103 Galactic Open Clusters". The Astronomical Journal. 158 (1). id. 35. arXiv:1905.04359. Bibcode:2019AJ....158...35S. doi:10.3847/1538-3881/ab21e1.
12. Frogel, J. A.; Twarog, B. A. (November 1983). "Faint stellar photometry in clusters. I. NGC 2204 and E3". Astrophysical Journal. 274: 270–285. Bibcode:1983ApJ...274..270F. doi:10.1086/161445.

External links

• NGC 2204 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images