NGC 2158

Also Known as:

Object Type: Open Cluster

Constellation: Gemini

Distance from Earth: 11,000 light years

Apparent Magnitude: 8.6

Coordinates: RA 04H 10M 31S DEC 69deg 52min 47sec

Actual Size: 16 light years in diameter

Apparent Dimensions: 5 arcminutes

Discovered by: About half a degree southwest of M 35 lies NGC 2158, discovered by William Herschel on 16 November 1784 using his selfmade 18.7 inch reflecting telescope.
He cataloged it as VI 17 (class VI = very compressed and rich clusters of stars) and noted: «A very rich cluster of very compressend extremely small stars. 4' or 5' diameter.
A miniature of the 35 cluster of the Connoissance des Temps which it precedes 1' 18" and is 2' north.»]

Description: NGC 2158 is a dense open cluster in Gemini, the "little brother" to M35.
Once thought to be a globular cluster because of its size and density, it is now known to be an intermediate-age, metal-poor open cluster that is a member of the old thin disk population.
Most open clusters are disrupted by tidal forces in only a few million years yet this cluster is thought to be nearly 2 billion years old.
As a result, its original hot blue stars have evolved off the main sequence leaving behind a redder population of stars.
It is, in angle, immediately southwest of open cluster Messier 35
The two clusters are unrelated, as the subject is around 9,000 light years further away.
NGC 2158 is a very rich and distant star cluster. Several thousand stars in an area of about five minutes of arc. The unusually large number of stars and their symmetrical distributions suggest that this is an intermediate stage from an open star cluster to a globular cluster, but the cluster does not show the central density typical of globular clusters.
The cluster is estimated to be over a billion years old, so the hottest stars in the main sequence are F0-type and it has many orange and red giants.
Too young for globular clusters, which are about ten times as old. The star cluster is thus on the outer edge of our galaxy.

Click Below Image(s) for Full Size:

NGC 2158 is a Open Cluster in the Gemini constellation. NGC 2158 is situated close to the celestial equator and, as such, it is at least partly visible from both hemispheres in certain times of the year.
Given its visual magnitude of 8.6, NGC 2158 is visible with the help of a binocular with a 60-70mm aperture or a small telescope.

Platesolve

NGC 2158 Open Cluster

Imaging Details
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