NGC 2129 is an
open cluster
An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...
in the
constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The origins of the e ...
Gemini
Gemini may refer to:
Space
* Gemini (constellation), one of the constellations of the zodiac
** Gemini in Chinese astronomy
* Project Gemini, the second U.S. crewed spaceflight program
* Gemini Observatory, consisting of telescopes in the Northern ...
. It has an
angular distance
Angular distance \theta (also known as angular separation, apparent distance, or apparent separation) is the angle between the two sightlines, or between two point objects as viewed from an observer.
Angular distance appears in mathematics (in pa ...
of 2.5
arcminutes
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...
and is approximately 2.2 ± 0.2
kpc (~7,200
light year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...
s) 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 (
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
A binary system is a system of two astronomical bodies which are close enough that their gravitational attraction causes them to orbit each other around a barycenter ''(also see animated examples)''. More restrictive definitions require that thi ...
.
See also
*
List of Messier objects
The Messier objects are a set of 110 astronomical objects catalogued by the French astronomer Charles Messier in his ''Catalogue des Nébuleuses et des Amas d'Étoiles'' (''Catalogue of Nebulae and Star Clusters'').
Because Messier was only int ...
*
List of NGC objects
The following is a list of NGC objects, that is objects listed in the New General Catalogue (NGC). It is one of the largest comprehensive astronomical catalogues for deep sky objects such as star clusters, nebulae, and galaxies.
* List of NGC objec ...
*
List of open clusters
This is a list of open clusters located in the Milky Way. An open cluster is a gravitationally bound association of up to a few thousand stars that all formed from the same giant molecular cloud. There are over 1,000 known open clusters in the Mil ...
*
General Catalogue of Nebulae and Clusters
A general officer is an officer of high rank in the armies, and in some nations' air forces, space forces, and marines or naval infantry.
In some usages the term "general officer" refers to a rank above colonel."general, adj. and n.". OED On ...
References
External links
*
* NASA/IPAC Extragalactic Database (NED)
NGC 2129*
Open clusters
Gemini (constellation)
2129
{{star-cluster-stub