| NGC 2129 | |
| Type: | Open Cluster |
| Epoch: | J2000 |
| Ra: | [1] [2] |
| Dist Ly: | 7,200 ly |
| Dist Pc: | 2,200 pc |
| Appmag V: | 6.7 |
| Size V: | 2.5 MOA |
| Radius Ly: | 5.2 |
| Absmag V: | -5.01 |
| Age: | 10 Myr |
| Constellation: | Gemini |
| Names: | NGC 2129, C 0558+233, OCl 467, OCISM 10, KPR2004b 84. |
NGC 2129 is an open cluster in the constellation Gemini. It has an angular distance of 2.5 arcminutes and is approximately 2.2 ± 0.2 kpc (~7,200 light years) from the Sun inside the Local spiral arm.[3] At that distance, the angular size of the cluster corresponds to a diameter of about 10.4 light years. NGC 2129 is a very young cluster whose age has been estimated at 10 million years.[3]
The group is dominated by two close B-Type stars, HD 250289 (B2III) and HD 250290 (B3I). With the two stars sharing the same proper motion and radial velocity it is likely that the two constitute a binary system.[3]