· · · ·

NGC 1981

Proper NameNone
Messier NumberNone
NGC/IC NumberNGC 1981
Right Ascension5h 35m 9s
Declination-4° 25' 54"
Distancec.1,300 light years
c.400 parsecs
MagnitudeApparent: +4.2
Absolute: -3.7
DiameterApparent: 22'
Actual: 8 light years
Number of Starsc. 40
Optimum VisibilityDecember / January
NotesThis cluster of about forty young blue stars lies directly to the north of the Orion Nebula. The stars of the cluster are spread over a region of the sky nearly half a degree across (only slightly less than the face of the Moon) but the individual stars of the cluster are too faint to be seen with the naked eye.

An Open Cluster that belongs to the complex of young stars and nebulous material that makes up the Sword of Orion. This cluster is easily located beneath Orion's Belt, and forms the northern end of the Sword. Moving northwards from the Orion Nebula, past the smaller Running Man Nebula, NGC 1981 sits at the northern end of the Sword formation: a prominent cluster of blue stars arranged in two approximate arcs, coming together to form a shape something like a rounded 'M' (the pattern formed by these stars is also sometimes compared to a crocodile or alligator).

The cluster and nearby nebulae are closely related to one another, arranged together at a distance of about 1,300 light years from Earth (NGC 1981 is in fact a matter for forty light years closer to Earth than its neighbouring nebulae). Some of the light by which we see the form of the Running Man Nebula to the south is reflected from the stars of the cluster.

NGC 1981 is young cluster of stars only recently formed from their surrounding nebula. Still glowing hot and blue, these stars are still surrounded by clouds of material, remnants of the nebula from which they originally formed. NGC 1981 is not a populous cluster, but its comparatively bright blue stars stand out distinctly against their background; indeed in many ways this cluster is reminiscent of the much closer Pleiades, though its relatively much greater distance means that at least binoculars are needed to fully appreciate its structure.


Related Entries