NGC 2204 | |
---|---|
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 |
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]
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]
Tarricq_et_al_2021
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