NGC 2129
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 from the Sun inside the Local spiral arm. 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.
The group is dominated by two close B-Type stars, HD 250289 and HD 250290. With the two stars sharing the same proper motion and radial velocity it is likely that the two constitute a binary system.
